Maher Arar, seen in a December 2006 photo, was detained in New York on Sept. 26, 2002, on his way home from a family vacation. He was later deported to Syria, where he was held for more than 10 months on suspicion of terrorist activity and tortured. (Fred Chartrand/Canadian Press)

Maher Arar said he was shocked and saddened to learn of allegations made at a U.S. military commission that he had lived with terrorists in Afghanistan.

Arar, a Canadian software engineer who was tortured in Syria after he was illegally sent there by the United States, responded for the first time Thursday to comments that were made at a hearing last week in Guantanamo Bay, Cuba, by a Federal Bureau of Investigation agent.

FBI special agent Robert Fuller testified at the trial of Canadian Omar Khadr that during interrogations in 2002, the teen said he recognized Arar in pictures and claimed to have seen him in Afghanistan in 2001.

Khadr is accused of killing a U.S. soldier in Afghanistan.

Fuller told the hearing that Khadr said he saw Arar at a safehouse in Kabul, and possibly at a training camp outside Kabul. Both facilities were run by al-Qaeda militant Abu Musab al-Siri.

Arar was a participant in a panel discussion put on by the Canadian Journalism Foundation Thursday in Toronto. During a scrum with reporters, he said he has only ever seen Khadr on television.

"It was shocking," Arar said. "I have to tell you, for a week at least I've been in a deep depression. It's not easy."

Arar was detained in New York on Sept. 26, 2002, while returning to Canada from a family vacation in Tunisia. He was then sent by the United States to Syria, where he was held and tortured for 10 months on suspicion of terrorist activity.

He has denied spending any time in Afghanistan and was cleared of any links to terrorism in 2006 after a commission of inquiry in Canada.

"The Khadr information was part of the inquiry documents," Arar said.

The Canadian government apologized and paid Arar $10.5 million in compensation but the Americans have refused to clear his name.

Arar is currently suing U.S. authorities for his "extraordinary rendition" to Syria.

Arar said Thursday he had initially refused to respond to the testimony given by the FBI agent at Khadr's trial because he didn't think it warranted a response. But he said he and his family have had "enough of this."

He said he was not particularly surprised to hear the allegations from the Americans at the trial in Guantanamo Bay.

"I'm not surprised because it happened many, many times," he said. "It will probably continue happening as long as the media is willing to publish those stories."

With files from the Canadian Press