U.S. authorities announced visa fraud charges against a Tunisian man who prosecutors said had met with a key figure in an alleged plot to blow up a railroad line in Canada that carries Amtrak trains between Toronto and New York.

In a letter filed in federal court in New York, prosecutors said the man, Ahmed Abassi, 26, who had lived in Canada, was recorded by a U.S. undercover agent discussing various "proposed terrorist plots" with Chiheb Esseghaier, another Tunisian suspect. Esseghaier is now being held by Canadian authorities.

Among the plots that Abassi allegedly discussed was "contaminating the air or water with bacteria in order to kill up to 100,000 people," prosecutors said in the letter. But they said that Esseghaier was "dismissive" of that plan and that no steps were ever taken to carry it out.

Instead, Canadian authorities said last month that they had arrested Esseghaier, 30, a doctoral student in nanotechnology at an institute near Montreal, with plotting to derail a train. A second man, Raed Jaser, faces Canadian charges in the same plot.
U.S. authorities said that in interviews with investigators, Abassi acknowledged that he and Esseghaier had discussed both poisoning a water supply and derailing a passenger train.

At a secret arraignment on May 2, Abassi pleaded not guilty to filling out false immigration documents, according to a newly unsealed transcript of the proceedings.

Abassi, wearing a jail jumpsuit, appeared on Thursday afternoon at a hearing in federal court in Manhattan. Standing more than 6-feet tall with a light beard, short black hair and wire-frame glasses, he leaned close to an Arabic interpreter throughout the hearing.

John Cronan, an assistant U.S. Attorney, said evidence would include "many, many hours" of recorded conversations with an undercover FBI agent, as well as statements Abassi made after being read his Miranda rights.

"Discovery will be voluminous," Cronan said.

At the time of their arrests, Canadian authorities said that Esseghaier and Jaser had received "direction and guidance" in the plot from "al Qaeda elements in Iran."

Reuters reported last month that investigators believe that Esseghaier traveled to Iran within the past two years, though they have not said why he went there or who he might have met.

Al Qaeda Figures in Iran
U.S. national security sources close to the investigation said that they believe one or more of the plotters were in contact with a network of low- to middle-level al Qaeda fixers and "facilitators" based in the town of Zahedan, close to Iran's borders with Afghanistan and Pakistan, that moves money and fighters through Iran to support its activities in South Asia.
Canadian police say there is no sign of Iranian government involvement with the suspects.

However, in the letter filed Thursday, U.S. prosecutors said that the American undercover agent had recorded discussions between Abassi and Esseghaier in which Abassi allegedly "discussed his desire to engage in terrorist acts against targets in the United States and other countries."

They also said that he had been recorded discussing his desire to provide support and funding to militant groups, including the al Nusrah front, an Islamist group the U.S. says is a front for al Qaeda in Iraq and which is one of the most powerful rebel factions fighting to oust Syrian President Bashar al-Assad.

Prosecutors said Abassi admitted he may have been responsible for radicalizing Esseghaier, and that he came to the United States in mid-March, where he remained until his arrest on April 22.

In their letter, prosecutors said investigators had briefly questioned Abassi under a "public safety" procedure that allows interrogation of suspects for intelligence purposes without advising them of Miranda rights.

But Abassi, before having a lawyer, on several