Canada stands almost alone as a country that has "abandoned" its citizens in the U.S. military's Guantanamo Bay prison, Amnesty International charged Thursday, presenting an open letter demanding Ottawa act to repatriate Omar Khadr.

The letter to Prime Minister Stephen Harper — signed by 111 legal academics and endorsed by 25 prominent Canadian politicians current and former — accuses the Canadian government of remaining silent on human rights violations of prisoners at the U.S. naval prison in Cuba.

The letter says Canada should "follow the precedent of other U.S. allies and insist on the repatriation of Khadr," who is the only Canadian being held at Guantanamo Bay.

Khadr, who was born in Canada to foreign-born parents and whose family lives in the Toronto area, has been in U.S. custody since he was arrested at age 15 in 2002. He was accused of throwing a grenade that killed an American medic in Afghanistan.

"His case now almost stands alone in terms of individuals who have been abandoned by their governments," Alex Neve, the secretary general of the Canadian arm of Amnesty International, said at a news conference in Ottawa, after releasing the letter.

Neve asked why Ottawa seemed "so reluctant" to protect its citizens when countries such as Australia were able to pressure Washington to transfer their detained citizens home.

Among the names listed on the open letter to Harper were former prime minister Joe Clark and former foreign affairs ministers Bill Graham and Lloyd Axworthy.

"Governments throughout Europe, the Australian government in the case of David Hicks [an Australian citizen repatriated in May], have all intervened forcefully and, generally, successfully," Neve said.

"British nationals have been returned to Britain, David Hicks recently returned to Australia … but even though everyone seems to get it, Canada still remains silent."

Last week, a U.S. military commission dropped all charges against Khadr, ruling that the courts did not have jurisdiction to try him as an "unlawful enemy combatant" since he was only classified as an "enemy combatant."

However, Khadr remains in detention in Cuba without charge while Washington considers the next step, which could involve an appeals process.

In the letter, Amnesty International said Canada's justice system — not a process "devised by the United States" — should try Khadr for his alleged crimes, "bearing in mind his age at the time the alleged acts occurred." Khadr was a minor when he was arrested on the battlefield.

The human-rights group said Canada should speak out against the U.S. military commissions process, which it dismissed as "invented on an ad hoc basis" without any bearing on international law.

At the press conference, Ottawa University law professor Craig Forcese said the dismissal of the case was "the final straw" and proved the commissions have been a failure.

Forcese said Canada must now "exercise diplomatic duty and bring [Khadr] back where he can serve a fair trial."

Repatriation 'premature' Emerson says

During Thursday's question period, Minister of International Trade David Emerson said repatriation for Khadr was "premature."

NDP justice critic Joe Comartin raised the issue of Khadr's detention, blasting Canada's actions so far.

"Not once has this government, has Canada, protested the use of military commissions nor done anything to get him home. If the British, Australian, French and Germans can get protection from the government, why won't the Conservatives do something for a Canadian in need at this time?"

Emerson said the Conservatives have been looking out for Khadr's well-being, through a discussion between Foreign Affairs Minister Peter MacKay and U.S. Secretary of State Condoleezza Rice. This discussion included requests for Khadr to have better access to his family, legal counsel and educational materials.

As well, foreign affairs officials have carried out welfare visits, and will continue to do so.

But on the issue of repatriation, Emerson said, "I think the House knows the allegations against Mr. Khadr are very serious and the question of accepting a repatriation of Mr. Khadr is premature, and it's speculative at this time."