Mere weeks after being freed from his ordeal as a hostage in Iraq, James Loney has taken on the cause of five detainees suspected of having links to Islamic terrorism.

The 41-year-old peace activist said he finds it repugnant that people can be incarcerated for years without charges and based on secret evidence they are not even permitted to see.

The detainees -- Adil Charkaoui, Mohamed Harkat, Hassan Almrei, Mahmoud Jaballah and Mohammed Mahjoub -- were arrested several years ago under immigration security certificates.

The security-certificate provision will be the subject of a three-day hearing at the Supreme Court of Canada late this month.

Unlike his own ordeal, Mr. Loney said, the detainees at least know where and why they are being held. "But any unjust deprivation of a person's liberty is an outrage," he said in an interview.

"Having experienced this myself has helped me see their situation in a very tangible way."

Mr. Loney said that three of the detainees -- Mr. Jaballah, Mr. Mahjoub and Mr. Almrei -- wrote an open letter while he was being held hostage in which they implored his hostage-takers to release him. In the letter, he said, the three men stated: "We care more about his freedom than about our own."

Mr. Loney said he was amazed when he heard about the letter, considering that the detainees face enormous problems because they are separated from their families and face the possibility of being deported.

Mr. Charkaoui was released on bail in February last year and Mr. Harkat was released last week, but the other three remain behind bars and are on a hunger strike.

Mr. Loney, a native of Sault Ste. Marie, Ont., intends to join a caravan of protest that leaves Toronto this weekend as part of a public crusade against security certificates.

It is scheduled to arrive in Kingston late next week, then continue to Ottawa, arriving at the Supreme Court of Canada.