AKCAKALE, Turkey — Syrian rebels seized control of a border crossing on the frontier with Turkey on Wednesday, ripping down the Syrian flag as the rebels fighting to oust President Bashar Assad expand their control of the country's north.

Assad, meanwhile, told Iran's visiting foreign minister that the fight against his government "targets resistance as a whole, not only Syria," an apparent reference to countries and groups opposed to Israel's existence. The "axis of resistance" includes Syria and Iran, along with the Shiite Muslim Hezbollah group in Lebanon and the Palestinian militant Hamas in the Gaza Strip.

The Iranian visitor, Ali Akbar Salehi, arrived in Syria after a visit to Cairo as part of an Egyptian-sponsored Syria peace initiative grouping Turkey, Saudi Arabia and Egypt – all supporters of the rebels – with Iran.

Egyptian President Mohammed Morsi warned Iran on Tuesday that its support for the Syrian regime was hurting chances of better relations between Iran and Egypt. The promise of greater rapprochement with Egypt is part of a package of incentives and efforts by Morsi to lure Iran, Syria's staunchest regional ally, away from Damascus and find an end to the bloodshed.

After meeting with Assad on Wednesday, the Iranian foreign minister pledged his country's "unwavering support" to Syria to end the fighting, according to the Syrian state news agency SANA. Although 18 months of bloodshed prompted international sanctions that have isolated Assad's government, the regime still has the support of Russia, Iran and China.

Assad, in turn, said "the success of any initiative is the truthful intention to help Syria," SANA said. It quoted Assad as saying that the "current battle targets resistance as a whole not only Syria." Syria is Iran's key ally in the Arab world, and a collapse of the Assad regime would be a major blow to attempts by Shiite-run Iran to expand its influence in the region.

In Washington, the Obama administration identified 117 Iranian aircraft it said are ferrying weapons to the Syrian regime. The planes operated by Iran Air, Mahan Air and Yas Air are delivering weapons and Iranian forces under the cover of "humanitarian" shipments, the Treasury Department said.

The airlines are already subject to U.S. sanctions: Americans cannot do business with them and any assets they have in the U.S. are frozen. But the U.S. is now listing planes individually, partly to pressure Iraq to crack down on Iranian weapons shipments to Syria via Iraqi airspace.

Baghdad insists it will not allow its airspace for arms shipments from Iran to Syria. Earlier this month, the Iraqi government said Iran had assured it that the flights to Syria were delivering only humanitarian aid, and called on the United States to prove otherwise.

The conflict in Syria began with peaceful protests that were attacked by government security forces and has since evolved into a civil war. Activists say at least 23,000 people have been killed. Rebel factions have also been accused of summary executions and other abuses.

In recent weeks, Syria's military has stepped up air attacks on rebel-held areas, but has failed to drive opposition fighters out of territories they have seized, particularly in Syria's north, near the border with Turkey.

Wednesday's capture of a border crossing with Turkey was a strategic boost for the rebels, allowing them to ferry supplies into the country as the fighters try to tip the balance in the civil war.

Syria's rebels have captured several other crossings into Turkey, as well as one on the border with Iraq. The seizure on Wednesday is believed to be the first time they have overrun a frontier post in the northern province of Raqqa, which could help in the fight for control of Aleppo, Syria's largest city, about 100 miles (160 kilometers) away.

"I am a free Syrian!" Zisha Bargash shouted, throwing his hands in the air as he watched the takeover from the Turkish side. "This is the beginning of the end Assad. Game over."

Bargash was among a dozen people – some jubilant, some wounded – who managed to crawl under a barbed wire barrier between the countries. Some replaced the national flag with a rebel banner, sparking loud cheers and applause.

Turkish officials cordoned off the area on the Turkish side of the border, and police prevented a crowd of people from trying to storm the area and cross into Syria.

Rebel fighter Sheikh Ahmed said rebels would push back against any Syrian army attempts to retake the crossing. "We're staying here no matter what," Ahmed said, speaking on the Syrian side of the border. "We are free."

Although the rebels appeared firmly in control of the crossing, scattered gunfire was heard on the Syrian side and a government flag was flying in the distance, suggesting government forces were not far away.

The takeover of the Tal Abyad crossing came after a day of fierce clashes as rebels and regime forces fought for its control.

Civilians fleeing the violence reported that several people were killed in the fighting around Tal Abyad, the private Turkish news agency Dogan reported. Several others were wounded in the battles and were taken to Turkey for treatment, the report said without giving specific numbers.

The conflict in Syria has sent refugees pouring into neighboring countries. Some 83,000 refugees have found shelter in 12 camps along the Turkish border with Syria.

In other developments, two bombs exploded Wednesday in a Damascus suburb, causing civilian casualties, according to SANA. The first blast went off near a secondary school in the Damascus suburb of Qudsayya, followed by a second explosion about 200 meters (yards) away, SANA said. The agency said school students were not among those hurt but had no further details.

Syrian opposition groups said at least 75 Syrian civilians were killed in fighting on Wednesday, with heavy casualties reported in and around Damascus and in Aleppo, Syria's largest city. There has been a spike in casualties since the Assad regime stepped up airstrikes over the summer, with Syrian activists saying nearly 5,000 people were killed in August, the highest monthly total since the crisis began in March 2011. Activists' reports of casualties cannot independently be confirmed.

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Associated Press writer Albert Aji in Damascus contributed to this report.

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  • Syrian Regime

    Despite major defections and a July 18. explosion in Damascus that killed four top generals, including President Bashar Assad's brother-in-law, the regime's inner circle is still powerful and united against the opposition. Assad's inner circle includes his younger brother, Maher, who commands the forces in charge of protecting the capital. It also includes the heads of the four intelligence agencies playing a major role in the crackdown. Although regime forces lost parts of the northern city of Aleppo, Syria's largest, government troops still control most cities, while the opposition dominates large parts of the countryside. <em>Caption: This June 13, 2000, file photo shows Syrian President Bashar Assad, right, his brother Maher, center, and brother-in-law Major General Assef Shawkat, left. (AP Photo, File)</em>

  • Free Syrian Army

    The main rebel fighting force for more than a year, the Free Syrian Army includes lightly-armed volunteer militiamen and defectors from Assad's military. Its overall strength and structure is unclear, but tens of thousands are believed be loyal to the group. The rebels have control over some northern areas, allowing movement of fighters and supplies from Turkey and Lebanon. Anti-Assad forces have failed to maintain any strategic footholds in big cities, being driven back from key neighborhoods in Homs earlier this year and now apparently losing ground in the largest urban center, Aleppo. The battles also suggest only weak direction from central commanders - including Turkey-based Free Syrian Army leader Riad al-Asaad. <em>Caption: In this citizen journalism image provided by Shaam News Network SNN, taken on Sunday, Aug. 12, 2012, Free Syrian Army soldiers pose for a photograph, in Sarmada, Idlib province, northern Syria. (AP Photo/Shaam News Network, SNN)</em>

  • Syrian National Council

    Based in Istanbul, the SNC has emerged as the main political opposition to Assad and has pushed for international recognition as the legitimate representative of the uprising, despite rifts with other Syrian factions. The group also has been hit by internal feuds that have led some senior members to quit. The current leader, Abdelbaset Sieda, is a Swedish-based activist for Syria's minority Kurdish community. The SNC has gained support from many countries in the West and Arab world, but it has not galvanized international backing, and critics complain its senior leadership is made up mostly of exiles out of touch with their homeland. <em>Caption: The members of the Syrian National Council and its head Abdulbaset Sieda, center, arrive for a meeting with Turkey's Foreign Minister Ahmet Davutoglu in Ankara, Turkey, Monday, July 23, 2012.(AP Photo/Burhan Ozbilici)</em>

  • The National Coordination Committee for Democratic Change

    A rival to the SNC, the National Coordination Committee is led by opposition figures inside Syria, many of them former political prisoners. SNC members accuse the group of being far too lenient and willing to engage in dialogue with the regime. In turn, the National Coordination Committee accuses the SNC of being a front for Western powers and willing to open the door to the Muslim Brotherhood and other conservative Islamist factions. <em>Caption: Member of the National Coordination Committee for Democratic Change, Morhaf Mickael speaks during a meeting of Syrian opposition parties in Brussels on Sunday, June 24, 2012. (AP Photo/Virginia Mayo)</em>

  • International Alliances

    On Assad's side are traditional Shiite allies Iran and Lebanon's Hezbollah. <em>Caption: In this photo released by the Syrian official news agency SANA, Iran's Supreme National Security Council, Saeed Jalili, meets with Syrian President Bashar Assad in Damascus, Syria, Tuesday, Aug. 7, 2012. (AP Photo/SANA)</em>

  • International Alliances

    The regime also has important political cover from Russia and China, which have used their Security Council vetoes to prevent U.N. sanctions on Syria. <em>Caption: In this Jan. 25, 2005 file photo, Syrian President Bashar Assad, left, and Russian President Vladimir Putin shake hands during a signing ceremony in the Kremlin, Moscow. (AP Photo/Sergei Chirikov)</em>

  • International Alliances

    The rebels have built an array of regional support that includes the wealthy Gulf states - led by Iran rival Saudi Arabia - and neighboring Turkey, which offers key supply routes. The West also backs the rebel forces, but has so far opposed mobilizing international military support similar to the NATO-led airstrikes that helped topple Moammar Gadhafi's regime in Libya. <em>Caption: From left, Bahrain's Foreign Minister, Sheik Khalid bin AhmedI bin Mohammed al-Khalifa, Saudi Arabia's Foreign Minister Prince Saud al-Faisal, his Turkish counterpart Ahmet Davutoglu and United Arab Emirates' Sheikh Abdullah bin Zayed al-Nahayan seenduring a group photo during the Gulf Cooperation Council (GCC) Foreign ministers meeting in Istanbul, Turkey, Saturday, Jan. 28, 2012 (AP Photo)</em>

  • Foreign Fighters

    Syria has drawn foreign fighters just as other recent conflicts such as Iraq and Afghanistan. No credible count on them exists, but anecdotal evidence suggests foreigners are coming to fight Assad. Rebel commanders downplay the presence of foreign fighters, saying their cause is a purely Syrian uprising. Mohammed Idilbi, a Syrian activist based in Turkey, says foreign ranks include Libyans, Yemenis, Tunisians and Lebanese. On Saturday, Syria's official SANA news agency claimed four Libyans were among rebels killed in Aleppo. <em>Caption: In this Sept. 18, 2011 file photo, former rebel fighters celebrate as smoke rises from Bani Walid, Libya, at the northern gate of the town. (AP Photo/Alexandre Meneghini, File)</em>

  • Extremists

    U.S. officials and others worry that Syria could become a new foothold for insurgents inspired by al-Qaida. Assessing the degree of radical Islamic ideology in the civil war is impossible, but at least one group, the al-Nusra Front, has emerged and declared allegiance to the Free Syrian Army. Al-Nusra, or Victory, has claimed responsibility for several high profile attacks, including a double suicide bombing in March that killed 27 people in Damascus and the execution-style killing of a Syrian television presenter who was abducted in July. On Friday, U.S. intelligence officials said al-Qaida has advanced beyond isolated pockets in Syria and now is building a network of well-organized cells that could include several hundred militants. <em>Caption: This photo shows Al-Qaida's new leader Ayman al-Zawahiri in a still image from a web posting by al-Qaida's media arm, as-Sahab, Wednesday July 27, 2011. Al-Qaida's new leader has lauded protesters in Syria for seeking to topple the regime of President Bashar Assad. (AP Photo/IntelCenter) </em>