U.S. Plans Law Enforcement 'Surge' On Trains

Terror Cell In Hamburg

In an interview Sunday, Pakistan's Ambassador Husain Haqqani told ABC News that the plot's leaders had been identified and targeted.

Metro Police patrol the subway station at Union Station, in Washington, in this July 2005 file...

Metro Police patrol the subway station at Union Station, in Washington, in this July 2005 file photo. US authorities plan a law enforcement surge this week along Amtrak routes, an exercise called operation RailSafe, and the heads of the country's biggest mass transit systems were briefed today on the possible threat, all part of what is being called an abundance of caution.

(Mandel Ngan/AFP/Getty Images)
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"I think that several people who were involved in the plotting have been targeted, and the others are certainly on the radar of U.S., Pakistani and European intelligence services," Haqqani said.

Among the possible targets in the suspected European terror plot are pre-security areas in at least five major European airports, a law enforcement official told ABC News. Authorities believe terror teams are preparing to mount a commando-like attack featuring small units and small firearms modeled after the Mumbai attack two years ago that killed 175.

U.S. authorities say they have tracked one of the suspected German terror cells to the German city of Hamburg.

One suspect now in custody worked as a cleaner at the Hamburg airport, and others still being sought attended the same mosque in Hamburg where the 9/11 hijackers gathered.

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More from Brian Ross and the Investigative Team

To the amazement of US officials, it turns out the leader, the imam, of the mosque is the same man accused by the U.S. nine years ago of helping finance the 9/11 plot, Mamoun Darkazanli.

"The mosque went back to being a very radical place where people are recruited for attacks where attacks are discussed," said former White House national security official Richard Clarke, now an ABC News consultant, "and German intelligence apparently stopped looking closely at the mosque where a lot of 9/11 was planned."

Darkazanli, who was never charged by the Germans, declined to comment about the latest plot when approached by ABC News.

In France, the Paris prosecutor's office, which is in charge of terrorism cases, has confirmed that 12 people were arrested in two separate and unrelated operations.

Two men were arrested in Marseilles and a third in Bordeaux. The three are suspected of links to Al Qaeda, and of connections to a Frenchman of Algerian origin recently arrested in Italy with explosive material. The men are suspected of offering assistance to jihadists entering France after training in the Pakistani-Afghan area.

In a separate operation, eight men and a women arrested in Marseilles are reportedly suspected of involvement in arms and explosives trafficking. Some of those arrested had already served time for "association of criminals in relation with a terrorist organization."

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