BEIRUT — A rebel unit of army defectors launched a major offensive against security facilities in Syria's largest city of Aleppo, and anti-regime forces targeted air bases to try to reduce the military threat from the skies, activists said Friday.

The coordinated attacks by the Brigade of Free Syrians pointed to a higher-than-usual degree of planning by the rebels, suggesting that President Bashar Assad's opponents are becoming more brazen as the civil war deepens.

The Local Coordination Committees, an activist group that monitors violence and rights abuses in Syria, said rebels shot down a helicopter in the town of Sarmeen, in the northeastern province of Idlib. An activist in the area also reported a helicopter was downed.

The reports could not be independently verified, but if confirmed, it would be the second such aircraft to be downed by rebels this week. One helicopter was downed in Damascus on Monday.

Nearly 18 months into the uprising against Assad that has become a civil war with more than 20,000 people estimated to have been killed, the International Red Cross painted a grim picture of life in Syria. It said the humanitarian needs of civilians were rising and medical care was becoming more and more scarce.

"People fear for their lives every minute of the day," said Marianne Gasser, the head of the ICRC delegation in Syria, in a report released in Geneva.

"Every day, dozens of people are killed in the fighting, and increasing numbers of people succumb to their wounds, unable to obtain medical care because of the fighting and the lack of medical supplies, or simply because medical care is not available in their areas," she said.

The three coordinated attacks in the northern city of Aleppo began before midnight Thursday and ended Friday morning – two days after Assad conceded that his forces have been unable to quell the rebellion.

Weeks of intense bombardment by the Syrian military, including airstrikes and artillery shelling, have failed to dislodge the rebels. Instead, it seems to have emboldened them.

Assad's military, the backbone of his 12-year rule, is bogged down in a stalemate for control of Aleppo and unable to crush the rebels in the capital of Damascus and its suburbs. It also is fighting smaller-scale battles in the south and east.

Dubbed "Northern Volcano," the rebel offensive in Aleppo targeted an artillery training school, a compound of the feared air force intelligence, and a large army checkpoint, according to Mohammed Saeed, an activist based in the city, which is Syria's commercial capital. The offensive will focus on specific military and intelligence targets in Aleppo and the surrounding province of the same name, he added.

The three simultaneous attacks left an unspecified number of troops dead or wounded and badly damaged the top floor of the main, two-story building in the air force intelligence compound, Saeed said via Skype.

Rami Abdul-Rahman, director of the Britain-based Syrian Observatory for Human Rights, also said rebels killed and wounded regime forces at an air force compound in Aleppo's Zahraa neighborhood, but had no details on the other two attacks reported by Saeed.

Rebels seized several areas in Aleppo last month, signaling a turning point in the conflict because the region had long been spared major violence. Rebels also control much of the wider Aleppo province, including areas on the border with Turkey.

Rebels in northern Syria said they are fighting for control of an air base in Idlib province, the second such facility to come under attack this week. Activists say a third air base, also in the north, came under attack Friday, with rebels hitting it with mortar rounds, antiaircraft guns and rocket-propelled grenades.

Activists say the attacks on air bases are in response to the growing use of aircraft by the regime, possibly to bolster its firepower as troops are stretched thin due to fighting on a multitude of fronts. The rebels have no effective weapons against the regime's fighter jets and helicopter gunships, except for antiaircraft guns that they mostly use against ground troops.

"The regime's air power is severely restricting the movement of the rebels on the ground," said Saeed, the Aleppo-based activist. "We need anti-aircraft missiles, but we may never get them."

In an interview with a privately owned Syrian TV channel shown Wednesday, Assad said his military needed time to win the war, but claimed the conflict has drawn regional and international powers to the side of the rebels. Syrian authorities often cite Turkey, Saudi Arabia and Qatar as the rebels' main backers.

Fighting continued elsewhere in Syria on Friday, including Damascus, where intense battles have been raging for more than a month. The Observatory and the Local Coordination Committees also reported clashes and shelling between troops and rebels in the southern province of Daraa and the central region of Homs.

By late Friday, the observatory said as many as 100 people were killed across Syria.

Heavy clashes continued for a third day around the sprawling Abu Zuhour air base in Idlib province, the Observatory said. Fadi Al-Yassin, an Idlib-based activist, said there were unconfirmed reports that three fighter jets were damaged by rebel shelling.

Al-Yassin said the attacks on Abu Zohour and the Taftanaz air base Wednesday were designed to curtail the regime's air power. He said 10 military helicopters were badly damaged in Taftanaz. Grainy photos of damaged helicopters purportedly in Taftanaz were posted on the Internet this week. The authenticity of the images could not be independently verified.

"The objective of the attack on Abu Zohour is to damage the runway as well as the jet fighters," Al-Yassin said by satellite phone from Idlib.

Rebels said they shot down a fighter jet Wednesday in Idlib, and Al-Yassin said it was hit by gunfire shortly after it took off from Abu Zohour. The two pilots bailed out; one was captured and the second was killed by rebels when he tried to resist, he added.

Video posted online by the rebels showed a body in olive-drab pilot's fatigues with what appeared to be a head wound. A white parachute lay nearby.

The video could not be authenticated.

Saeed said another Aleppo-area airport, Quiras, came under attack Friday.

In Paris, French Foreign Minister Laurent Fabius warned that France would respond with military force if Assad uses his chemical weapons.

"Our response would be immediate and sharp as lightning," Fabius said Friday on Europe-1 radio, suggesting that France would not wait for U.N. permission.

"Bacteriological and chemical weapons are of a different nature from ordinary arms," he said. "We cannot tolerate that these weapons, whose fallout could spread, would be used."

Syria said in July that it could use chemical or biological weapons if it were attacked from outside.

Syria is believed to have nerve agents as well as mustard gas, Scud missiles capable of delivering these lethal chemicals and a variety of advanced conventional arms, including anti-tank rockets and late-model portable anti-aircraft missiles.

The U.N. refugee agency reported a growing number of Syrians fleeing to Lebanon's eastern Bekaa Valley, near the Syrian border, with about 2,200 arriving in the past week. That's almost double the weekly average, agency spokesman Adrian Edwards said.

Another 400 Syrians are reaching northern Lebanon each week, he said in Geneva.

Edwards said Turkey has opened two more refugee camps for Syrians in the past week and is now hosting 80,410 people in 11 camps and schools in its border provinces.

Also in Geneva, former U.N. Secretary-General Kofi Annan quietly ended his stint as a would-be peacemaker for Syria on Friday, with the task now being taken up by another veteran U.N. diplomat, Lakhdar Brahimi.

Unlike Annan, who was based in Geneva for six months, Brahimi will make his center of operations in New York, where he hopes he can better influence the U.N. Security Council to unite around a plan to end the violence.

Annan blamed divisions on the 15-nation Security Council for the failure to persuade Assad and the opposition to end the conflict.

Russia and China used their vetoes on the council to block U.N. sanctions against the Syrian regime, despite entreaties by the U.S. and other Western nations.

Brahimi, a former Algerian foreign minister who has been a U.N. envoy to Afghanistan and Iraq, said his first task will be to overcome the divisions in the Security Council and get it to speak "with a unified voice."

___

Associated Press writer Angela Charlton in Paris and Frank Jordans in Berlin contributed to this report.

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  • March 2011

    Protests erupt in the Southern city of Daraa after 15 young boys were arrested for spraying anti-government slogans on a city wall.

  • April 19, 2011

    In an attempt to ease the protests, the Syrian government passes a bill that lifts Syria's 48-year emergency rule. <br> <em>In this citizen journalism image made on a mobile phone and acquired by the AP, taken Monday April 18, 2011, Syrians pray in Clock Square in the center of the city of Homs, Syria. (AP)</em>

  • April 22, 2011

    Security forces and gunmen loyal to President Bashar al-Assad kill at least 100 protesters, rights group said. <br> <em>Syrian anti-government protesters gesture as they demonstrate following Friday prayers in the central city of Homs, Syria, Friday, April 22, 2011. (AP)</em>

  • May 23, 2011

    The European Union imposed sanctions on president Bashar Assad and nine other senior government officials.<br> <em>Syrian President Bashar Assad, seen, during a meeting with his Iranian counterpart Mahmoud Ahmadinejad, unseen, at the presidency in Tehran, Iran, Wednesday, Aug. 19, 2009. (AP)</em>

  • November 12, 2011

    The Arab League suspends Syria.<br> <em>General view of the Arab League emergency session on Syria at the Arab League headquarters in Cairo, Egypt, Saturday, Nov.12, 2011. (AP)</em>

  • December 7, 2011

    Assad denies ordering his troops to kill peaceful demonstrators, telling U.S. television channel ABC that only a "crazy" leader kills his own people.<br> <em>In this image from amateur video made available by the Ugarit News group on Wednesday, Dec. 7, 2011, the coffins of three protesters are carried during a march in Homs, Syria. (AP)</em>

  • December 27, 2011

    Arab League monitors said they saw "nothing frightening" during an initial visit to Homs, as 20,000 people held protests there. The monitor mission was part of an Arab League peace plan negotiated between the organization and the Assad regime to end the bloodshed in the country.<br> <em>In this image made from amateur video released by Shaam News Network and dated Wednesday Dec. 28, 2011, purports to show Arab League monitors visiting the Baba Amr area of Homs in Syria. (AP)</em>

  • January 28, 2012

    The Arab League suspends its monitoring mission while violence becomes increasingly gruesome.<br> <em>This citizen journalism image provided by the Local Coordination Committees in Syria and released on Friday Jan. 27, 2012, purports to show the bodies of five Syrian children wrapped in plastic bags, with signs in Arabic identifying them by name. (AP)</em>

  • January 31, 2012

    Government forces reasserted control over parts of Damascus as Syrian rebels withdrew, after three days of fighting that activists say killed at least 100 people.<br> <em>Syrian rebels hold their RPG and their guns as they stand on alert during a battle with the Syrian government forces, at Rastan area in Homs province, central Syria, on Tuesday Jan. 31, 2012. (AP)</em>

  • February 4, 2012

    Russia and China vetoed a resolution from the U.N. Security Council calling for Assad to step down.<br> <em>An anti-Syrian regime protester holds up a placard against Russia as others chant slogans during a midnight demonstration against Syrian President Bashar Assad, in the suburb of Kedssaya, in Damascus, Syria, on Saturday Feb. 4, 2012. (AP)</em>

  • February 16, 2012

    The U.N. General Assembly approved a resolution endorsing the Arab League plan calling for Assad to step aside.<br> <em>In this citizen journalism image provide by the Local Coordination Committees in Syria, anti-Syrian regime protesters hold an Arabic banner which reads "Homs is the city of the orphan Syrian revolution," as they march during a demonstration against Syrian President Bashar Assad, at Dael village in Daraa province, south Syria, on Friday, Feb. 17, 2012. (AP)</em>

  • February 22, 2012

    More than 80 people were killed in Homs including two foreign journalists, Marie Colvin and Remi Ochlik. Syrian security forces shelled Homs for nearly a month in an attempt to drive Syrian Free Army fighters out. Activists say hundreds of people have died in the siege. <br> <em>This is an undated image of journalist Marie Colvin, made available Wednesday, Feb. 22, 2012 by the Sunday Times in London. (AP)</em>

  • February 23, 2012

    Former U.N. Secretary-General Kofi Annan was appointed U.N.-Arab League envoy to Syria. <br>

  • February 27, 2012

    Opposition fighters leave the besieged neighborhood of Baba Amr in Homs. Government troops vow to 'cleanse' the neighborhood. <i>In this Tuesday, Feb. 21, 2012 citizen journalism image provided by the Local Coordination Committees in Syria and accessed on Wednesday, Feb. 22, 2012, black smoke rises into the air from Syrian government shelling, at Baba Amr neighborhood in Homs province, Syria. (AP Photo/Local Coordination Committees in Syria)</i>

  • February 28, 2012

    According to Assad, 90 percent of voters endorsed a new constitution in a referendum on February 26. The declaration was widely dismissed as a sham.<br>

  • March 8, 2012

    Syria's deputy oil minister announces his defection in a YouTube video.

  • March 14, 2012

    The Guardian obtains thousands of emails that appear to have been sent and received by Syrian president Bashar Assad and his wife Asma. <i>In this photo released by the Syrian official news agency SANA, Syrian President Bashar Assad casts his ballot next to his wife Asma at a polling station during a referendum on the new constitution, in Damascus, Syria, on Sunday Feb. 26, 2012. (AP Photo/SANA)</i>

  • March 15, 2012

    The U.N. estimates 8,000 people have been killed in the conflict. <i>In this March 9, 2012 citizen journalism image provided by the Homs City Union of The Syrian Revolution, smoke rise from a building that was shelled by the Syrian army, at Jeb al-Jandali neighborhood in Homs province, central Syria. (AP Photo/Homs City Union of The Syrian Revolution)</i>

  • March 25, 2012

    The UN raises the estimated death toll in Syria's conflict to 9,000. <i> This image made from amateur video and released by Shaam News Network Saturday, March 24, 2012, purports to show smoke rising after rockets fell in the Khaldiyeh area of Homs, Syria. (AP Photo/Shaam News Network via AP video) </i>

  • March 27, 2012

    Syria accepts a six-point peace plan offered by U.N.-Arab League envoy Kofi Annan.

  • April 9, 2012

    Syrian forces fire into a refugee camp across the Turkish border. <i>In this Monday, April 9, 2012 photo, Syrian refugees are seen in camp in Reyhanli, Turkey. (AP Photo/Germano Assad) </i>

  • April 12, 2012

    A U.N.-brokered ceasefire takes hold. Regime forces stop assaults, but fail to retreat from city centers. <i>Pro-Syrian government demonstrators hold a rally at Sabe Bahrat Square to commemorate the 65th anniversary of the foundation of the Ruling Baath Arab Socialist Party in Damascus, Syria, Saturday, April 7, 2012. (AP Photo Bassem Tellawi) </i>

  • April 14, 2012

    The U.N. Security Council approves a resolution to send observers to Syria to monitor the implementation of the ceasefire.

  • April 21, 2012

    The UN sends 300 observers to Syria for three months to monitor the "ceasefire." <em>In this photo released by the Syrian official news agency SANA, a UN observer and Syrian army officer, left, listen to Syrian citizens during their visit to the pro-Syrian regime neighborhoods, in Homs province, central Syria, on Monday April 23, 2012. (AP Photo/SANA)</em>

  • April 25, 2012

    A rocket attack on the city Hama kills 69, including some children. <em>In this image made from amateur video released by the Ugarit News and accessed Wednesday, April 25, 2012, purports to show Syrians standing in rubble of damaged buildings from Syrian forces shelling in Hama, Syria. (AP Photo/Ugarit News via AP video) </em>

  • April 27, 2012

    An explosion in the Midan neighborhood of Damascus, Syria kills 11 and injures 28. <em>Syrian investigators, right, gather next to a damaged police bus that was attacked by an explosion in the Midan neighborhood of Damascus, Syria, on Friday April 27, 2012. (AP Photo/Bassem Tellawi)</em>

  • May 7, 2012

    Parliamentary elections are held. While the regime sees the elections as an indication of its willingness to concede to democratic reforms, the opposition dismisses the elections as a sham. <em>In this photo taken during a government-organized tour, Syrian campaign workers wait outside a polling station during the parliamentary elections, in Damascus, Syria, Monday, May 7, 2012. (AP Photo/Muzaffar Salman)</em>

  • May 10, 2012

    Two explosions near a military intelligence complex in Damascus killed 55. <em>Syrian inspectors investigate the crater in front of a damaged military intelligence building where two bombs exploded, at Qazaz neighborhood in Damascus, Syria, on Thursday May 10, 2012. (AP Photo/Bassem Tellawi)</em>

  • May 25, 2012

    A massacre occurs in the village of Houla, where 108 people were killed. Activists blamed the regime for the massacre, although the Syrian government denies all responsibility. <em>This frame grab made from an amateur video provided by Syrian activists on Monday, May 28, 2012, purports to show the massacre in Houla on May 25 that killed more than 100 people, many of them children. (AP Photo/Amateur Video via AP video)</em>

  • More explosions in Hama kill scores more. <em>In this citizen journalism image provided by Sham News Network SNN and according to them, purports to show the bodies of Syrian children in Mazraat al-Qubair on the outskirts of Hama, central Syria, Thursday, June 7, 2012. (AP Photo/Shaam News Network, SNN)</em>

  • June 12, 2012

    The head of the UN peacekeeping operations, Herve Ladsous, calls the Syria crisis a "civil war." <em>A Nepalese human rights activist holds a placard against the human rights violation in Syria as they take part in a protest organized by the Amnesty International outside the United Nations office in Katmandu, Nepal, Wednesday, June 13, 2012. (AP Photo/Niranjan Shrestha)</em>

  • June 22, 2012

    Syria shoots down Turkish warplane, for which Syrian President Bashar Assad expressed regret. <em>In this April 29, 2010 file photo, a Turkish pilot salutes before take-off at an air base in Konya, Turkey. (AP Photo/File)</em>

  • June 26, 2012

    Assad announces that his country is in a state of war. <em>In this image taken from TV Syria's president Bashar al-Assad speaks during an interview in Tehran, Iran, Thursday June 28, 2012. (AP Photo/IRIB TV via APTN) </em>

  • July 6, 2012

    General Manaf Tlas, son of Mustafa Tlas and a member of Assad's inner circle, defects and flees to France. <em>In this Feb. 22, 1971 file photo, Army Chief of Staff Gen. Mustafa Tlas (front row, 2nd from right) and Air Force General Naji Jamil (1st right) surrounded by other members of Parliament on election day in Damascus, Syria. (AP Photo, File)</em>

  • July 11, 2012

    Nawaf al-Fares, Assad's ambassador to Iraq, defects and joins the Syrian opposition. <em>In this Sept. 16, 2008 file photo provided by the Syrian official news agency SANA, Nawaf Fares, left, is sworn in as Syria's ambassador to Iraq before Syrian President Bashar Assad, right, and Syrian Foreign Minister Walid Moallem in Damascus. (AP Photo/SANA, File)</em>

  • July 12, 2012

    Up to 200 people, most of them civilians, are killed in the village of Tremseh. The massacre is condemned by the international community. <em>In this citizen journalism image provided by Shaam News Network SNN, taken on Saturday, July 14, 2012, a woman holds a child in front of their destroyed home in Tremseh, Syria about 15 kilometers (9 miles) northwest of the central city of Hama. (AP Photo/Shaam News Network, SNN)</em>

  • July 18, 2012

    Former Defense Minister Hassan Turkmani, Syrian Defense Minister Gen. Dawoud Rajha, and Bashar Assad's brother-in-law Major General Assef Shawkat are killed in a bomb attack on Damascus. <em>This undated combo image made of 3 photos released by the Syrian official news agency SANA, shows former defense minister Hassan Turkmani, left, Syrian Defense Minister Gen. Dawoud Rajha, center, and Bashar Assad's brother-in-law Major General Assef Shawkat, right, in Damascus, Syria. (AP Photo/SANA)</em>

  • July 12, 2012

    Activists say more than a hundred people were killed in the village of Tremseh, near the city of Hama. <em>In this citizen journalism image provided by Shaam News Network SNN, taken on Saturday, July 14, 2012, a woman holds a child in front of their destroyed home in Tremseh, Syria about 15 kilometers (9 miles) northwest of the central city of Hama. (AP Photo/Shaam News Network, SNN)</em>

  • August 6, 2012

    Syria's prime minister Riyad Hijab defects and flees to Jordan. <em>Riad Hijab, Syria┬'s defected former prime minister, speaks at a press conference at the Hyatt Hotel in Amman, Jordan, Tuesday, Aug. 14, 2012. (AP photo/Mohammad Hannon)</em>