Al-Qaeda is plotting attacks on Europe's high-speed rail network, German mass circulation daily Bild reported on Monday, citing intelligence sources.
The extremist group could plant explosives on trains and tunnels or sabotage tracks and electrical cabling, said Bild, Europe's most widely read daily.
Bild said the information came from the National Security Agency (NSA) in the United States, which had listened in to a conference call involving top Al-Qaeda operatives.
The attacks on Europe's rail network was a "central topic" of this call, Bild said.
Authorities in Germany have responded to the threat with discrete measures such as deploying plain-clothed police officers at key stations and on main routes, according to the daily.
According to US media reports, intelligence services intercepted a conference call earlier this month between Al-Qaeda leader Ayman al-Zawahiri and more than 20 operatives from across the group's global network.
This prompted the US and several allies to shut embassies across the Muslim world, fearful of a major attack.
On August 1, the US issued a worldwide alert, warning of Al-Qaeda plans to launch an attack in the Middle East or North Africa.
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Once Osama bin Laden's aide-de-camp, Wahishi is the top leader of AQAP. In February 2006, Wahishi was among 23 al-Qaeda militants who broke out of a detention facility in Sanaa, Yemen's capital. In May 2011, al-Wahishi posted a eulogy for the slain al-Qaeda leader on Islamic extremist websites in which he warned Americans "the matter will not be over" with bin Laden's death and that "what is coming is greater and worse." He said "jihad is glowing brighter" now than during bin Laden's life. Three months later, he vowed to continue the fight against the regime and Western powers. He condemned U.S. drone attacks on Yemen, which have killed civilians, and the "silence" of Yemen's leaders to these attacks. "My soldiers and those soldiers with me in the Arab gulf... will not give up nor give in until Islam is ruling by God's will and strength," al-Wahishi said. "Our war against the Zionist Crusaders remains, for they have chosen this war." <em>This file image provided by IntelCenter on Wednesday Dec. 30, 2009 and taken from a video released Jan. 23, 2009 by al-Malahim Media Foundation, the media arm of al-Qaeda in the Arabian Peninsula, shows a man IntelCenter identifies as Nasser al-Wahishi, the leader of the group. (AP Photo/IntelCenter, File)</em>
Al-Raimi became the group's military commander and the brains behind a series of foiled attacks against Americans. In writings and videos, he vowed to topple Saleh's regime and to strike America. The Yemeni government has incorrectly announced al-Raimi's death three times in strikes or clashes since 2007. Even on the run, he directs training camps in Yemen's remote deserts and mountains, organizes cells and plans attacks at home and abroad, according to Yemeni officials. <em>Qassem al-Raimi, right, and Muhammed al-Dailami, left, speak to the court during the second session of the appeal to their jail sentences, San'a, Yemen, Saturday, Dec.11, 2004. (AP Photo/Muhammed Al Qadhi, courtesy the Yemen Times)</em>
Ibrahim Hassan Al-Asiri
Al-Asiri is AQAP's chief bomb-maker, responsible for building the underwear bomb used to try to bring down a Detroit-bound jetliner on Christmas in 2009 and the printer-cartridge bombs intercepted in U.S.-bound cargo planes a year later. U.S. intelligence officials say he has resurfaced recently in Yemen, after months in hiding. <em>This undated file photo released by Saudi Arabia's Ministry of Interior on Sunday, Oct. 31, 2010, purports to show Ibrahim Hassan al-Asiri. (AP Photo/Saudi Arabia Ministry of Interior, File)</em>
The 40-year-old American-Yemeni cleric emerged as an enormously influential preacher among militants living in the West, with his English language Internet sermons calling for jihad, or holy war, against the United States. He was in contact with the accused perpetrators of the 2009 shooting rampage at Fort Hood, Texas, that killed 13 people, the 2010 car bomb attempt in New York's Times Square and the Christmas 2009 attempt to blow up an airliner heading to Detroit. Al-Awlaki was killed on Sept. 30, 2011 in a drone strike in the mountains of Yemen. <em>In this Nov. 8, 2010 file image taken from video and released by SITE Intelligence Group on Monday, Anwar al-Awlaki speaks in a video message posted on radical websites. (AP Photo/SITE Intelligence Group, File)</em>
Muhammad, 28, is serving a life prison sentence for the June 2009 fatal shooting of a soldier outside a Little Rock, Ark., military recruiting station. Muhammad, who changed his name from Carlos Bledsoe when he converted to Islam, grew up in the Memphis, Tenn., area and then traveled to Yemen, returning to the U.S. in 2008. Muhammad has described himself as a soldier in al-Qaeda in the Arabian Peninsula and called the shooting "a jihadi attack." <em>In this July 7, 2010 file photo, Abdulhakim Muhammad is escorted to a hearing at the Pulaski County Court House in Little Rock, Ark. An Arkansas Department of Correction spokeswoman said Friday, Oct. 19, 2012, that corrections officers found a piece of metal in Muhammad's mattress during a routine search in April. (AP Photo/Danny Johnston, File)</em>
Major Nidal Hasan
Hasan, 42, a U.S.-born Army psychiatrist of Palestinian descent, is accused in the 2009 shooting rampage that killed 13 people at the Army post in Fort Hood, Texas. The Hasan case prompted a slew of finger-pointing among government agencies over why more action wasn't taken when red flags appeared, particularly his e-mail contact with a radical cleric in Yemen. <em>This undated file photo provided by the Bell County Sheriff's Department shows Nidal Hasan, who is charged in the 2009 shooting rampage at Fort Hood that left 13 dead and more than 30 others wounded. (AP Photo/Bell County Sheriff's Department, File)</em>
Sharif Mobley, 29, a New Jersey man of Somali descent is imprisoned in Yemen, suspected of ties to al-Qaeda and killing a guard in a failed escape attempt. During his time in the United States, Mobley passed a criminal background check and worked as a laborer at a number of nuclear power plants. There is no indication that his work had any connection to his alleged involvement with terrorists. A former friend said Mobley became increasingly radicalized in his Muslim beliefs before he moved to Yemen. <em>This 2002 photo provided by Roman Castro shows Sharif Mobley, 26, at a barbecue in Buena, N.J. (AP Photo/Roman Castro, File)</em>