Former Guatanamo detainee Moazzam Begg, centre, speaks at a conference in London in 2009. He was barred from a London-to-Toronto flight Friday after Air Canada cited U.S. security concerns. Akira Suemori/Associated Press

A former Guantanamo Bay detainee who never faced charges was barred from a London-to-Toronto flight Friday after Air Canada cited U.S. security concerns, according to a prominent lawyer.

Dennis Edney, who represents Canadian Guantanamo detainee Omar Khadr, had invited Moazzam Begg to speak at a conference Saturday on fear and justice and building bridges between Muslims and other communities.

Begg, a British man who was released from Guantanamo in 2005 and has since become an advocate for Guantanamo prisoners' rights, attempted to fly from London to Toronto on Friday morning.

But Air Canada told him the Canadian High Commission refused him permission to board on the basis that the plane "could be re-routed to the United States," Edney said.

"He's disappointed," Edney said of Begg. "He has a sense of Canada that may not be there. He has a sense that we stand up for rights and justice, that we're that kind of people. The reality is we take our orders from the United States."

The U.S. has accused Begg of being a member of al-Qaeda, as well as recruiting for them, attending training camps and sending money and support.

Begg admits to supporting militant Muslims in Bosnia, Chechnya and Kashmir, but says he does not support suicide bombers or the Sept. 11 attacks. He even admits to buying a handgun in Afghanistan, but says he never received military training or planned to fight.

Airlines that operate from Canada have been known to reject passengers whose names are on the U.S. no-fly list. That's because many flights pass over American airspace or may be forced to land at a U.S. airport in the event of an emergency.

Under the U.S. Secure Flight program, Canadian airlines now submit the name, gender and birthdate of passengers to the U.S. Transportation Security Administration for any flight passing over U.S. airspace.

In February, another British man was told he couldn't fly home from Toronto. Dawood Hepplewhite suspected he is on the no-fly list because he's a white Muslim and attended a job interview in Yemen.

Edney said he contacted the high commission and was told to contact the U.S. Embassy, and was unable to reach Citizenship and Immigration Minister Jason Kenney.

Prior to trying to fly to Canada, Begg had no concerns about his journey, having travelled to several other countries. He has also been recognized for his work by high-profile European politicians, notably by the U.S. ambassador to Luxembourg in a leaked diplomatic cable.

Air Canada did not immediately respond to a request for comment.

© The Canadian Press, 2011