TORONTO - A suspected Syrian terrorist who has spent seven years in mostly segregated custody is arguing his indefinite detention without charge or trial amounts to cruelty.

In a challenge filed in Federal Court, lawyers for Hassan Almrei argue his lengthy incarceration violates his constitutional rights.

"It's seven years and we're saying it's unconstitutional," said Toronto lawyer Lorne Waldman, who represents Almrei, said Sunday.

"It's cruel and inhumane treatment."

Speaking from Argentina, Waldman confirmed the challenge filed Friday will form part of a two-day bail hearing slated to start Oct. 2.

Almrei, who has travelled to Saudi Arabia, Afghanistan and Pakistan, was arrested in the aftermath of the horrendous terrorist attacks in the United States in September 2001.

He was linked to former Toronto resident Nabil al-Marabh, for whom he procured a fake Canadian passport. Initially touted by American security officials as a Canadian connection to the 9/11 attacks, Al-Marabh was convicted in the United States in 2002 of a routine immigration violation and deported to Syria in 2004.

Almrei is one of five Muslim foreigners held under a national security certificate - which allows the federal government to detain them indefinitely as a threat to Canada's public safety based on secret evidence.

The other four, all who have family to act as sureties, have been granted bail under stringent conditions while their lawyers fight Ottawa's contention they have terrorist ties.

Almrei, 34, who is single, remains behind bars in an immigration holding centre in Kingston, Ont. October 17 will mark his seventh year in custody.

"He's served . . . more than most murderers serve having never been convicted of an offence in Canada," Waldman said. "It's shocking."

Secret hearings on whether the national security certificates are "reasonable" are slated to resume in the fall amid ongoing legal clashes about the fairness of the entire process.

To address Supreme Court of Canada misgivings, the government of Prime Minister Stephen Harper revamped the legislation earlier this year to allow the appointment of "special advocates."

The security-cleared lawyers are allowed to see the secret evidence so they can challenge its validity before a judge behind closed doors.

Ottawa argues the revamped legislation strikes the fine balance between national security interests and fairness to the detainees.

But special advocates - some of the country's most experienced lawyers - argue gag orders in the legislation make it impossible to do their jobs advocating for the detainees.

They are fighting parts of the law that forbid them from communicating with the detainees or their public lawyers about the confidential information or "the proceeding."

"The government did have a choice as to which model to use and they took the minimalist approach," Waldman said.

"It's extremely unfortunate, because by taking that approach, they've left the door open for all sorts of constitutional challenges that could have been avoided."

The challenge to the gag provisions is expected to be heard later this month.

Besides Almrei, Mahmoud Jaballah, Mohammad Mahjoub, Mohamed Harkat and Adil Charkaoui are also being held under national security certificates.

All five deny terrorist links and have fought deportation based on substantial fears of torture if returned to their home countries, which include Egypt and Algeria.