Islamist terror network Al-Qaeda is plotting attacks on Europe's high-speed rail network, German newspaper Bild reported on Monday, citing U.S. intelligence sources.
The group could plant explosives on trains and tunnels or sabotage tracks and electrical cabling, said the newspaper, which is Europe's most widely-read daily.
The information reportedly came from the National Security Agency (NSA) in the United States, which had eavesdropped on a 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 discreet measures such as deploying plain-clothes police officers at key stations and on main routes, according to the report.
U.S. media reports earlier this month said that intelligence services intercepted a conference call 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 that a major attack was imminent.
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.