In this May 13, 2015 photo, former Guantanamo detainee and al-Qaida trainee Mourad Benchellali talks during an interview with the Associated Press in Gennevilliers, suburban Paris, France.

Mourad Benchellali, a French national and former Guantanamo Bay inmate, was detained by Canadian police at a Toronto airport on Monday on his way to a conference, his lawyer said on Wednesday.

Benchellali, who is now an anti-extremism activist, was set to attend a conference in Canada on preventing radicalization in prisons, but local authorities still consider him a “threat to national security,” Radio-Canada reported. His lawyer confirmed the Radio-Canada report, but did not comment further.

A Canadian Border Services Agency (CBSA) spokesman could not immediately confirm the detention, but the filmmaker who had invited Benchellali to Canada to be part of a documentary she is producing said he was now detained in a maximum security prison.

Toronto-based filmmaker Eileen Thalenberg said by phone on Wednesday that she invited Benchellali to be part of a documentary she is producing for the Canadian Broadcasting Corp because of his prevention work with youth.

Thalenberg said she checked with the Royal Canadian Mounted Police and received assurances before bringing Benchellali from France to Iceland and then to Canada, so he would not fly over American airspace.

“I would have never brought him otherwise,” she told Reuters.

The RCMP declined to comment, referring queries to the CBSA, which did not immediately respond to a request for comment.

Thalenberg said Benchellali sent her a text message from prison on Wednesday saying: “I never thought I’d be in an orange jumpsuit again.”

Originally from a suburb of Lyon, Benchellali was arrested at an Al Qaida training camp in Afghanistan and taken into custody by the U.S. army. He was an inmate at Guantanamo from January 2002 to July 2004.

For the past two years he has been involved in an initiative to stop young people from joining terror groups in Syria, according to his supporters.

Benchellali was previously stopped from boarding a flight to Canada in June because he is still on the U.S. government’s no-fly list and the plane would have passed through U.S. airspace.

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