SAN JUAN, Puerto Rico - Canadian detainee Omar Khadr has fired his American lawyers, leaving himself without defence counsel ahead of his trial.

His former military lawyer, U.S. Marine Lt.-Col. Colby Vokey confirmed he had been taken off the case on Wednesday.

He does not trust his American lawyers, Volke said, adding that he does not blame Khadr for the decision.

Volke said the United States is responsible for Khadr's interrogation and his treatment under a process that is "patently unfair.''

Khadr was 15 when he was captured in a firefight in Afghanistan in which he allegedly killed a U.S. Army special forces soldier with a grenade.

He is scheduled to be arraigned on Monday at the isolated base in southeast Cuba.