OTTAWA - Opposition parties are again demanding that the Conservative government act to bring Omar Khadr home from Guantanamo, Cuba.

The Liberals, Bloc and NDP are all issuing renewed calls for the return of the 22-year-old Canadian who has been detained at the U.S. military base since he was captured in Afghanistan in 2002.

The parties say it makes sense to repatriate Khadr since president-elect Barrack Obama has promised to close the controversial Guantanamo jail.

He is the last western citizen held in Guantanamo after other countries successfully lobbied the United States for the return of their nationals.

The opposition politicians say returning Khadr, a minor at the time of the incident, to Canada will ensure his rights are protected.

The Toronto-born Khadr is on trial before an American military tribunal on a charge of killing a U.S. army medic.

His lawyers argue the United States has no right to try him because he was only 15 when he allegedly threw a grenade that killed an American medic.

"Mr. Khadr's continued imprisonment in Guantanamo Bay is simply indefensible," said Bryon Wilfert, the Liberal foreign affairs critic.

"With the pending closure of the controversial facility under the incoming Obama administration, the Conservatives must take action to ensure that Mr. Khadr is transferred to Canada, where justice can be carried out before a fair and impartial tribunal".

Paul Dewar of the NDP said Khadr shouldn't be in front of a tribunal at all.

"Both the Supreme Court of Canada and the U.S. Supreme Court, with the benefit of a full factual record, have found that the military commission proceedings to which Mr. Khadr has been subjected violate U.S. domestic law and Canada's international human-rights obligations," he said.

"Rather than engaging in this process, Canada should seek to arrive at an alternative resolution of Mr. Khadr's case, which relies on settled and secure legal mechanisms."