Arrangements between the United States and Australia to allow Guantanamo Bay detainee David Hicks to serve a prison sentence on terrorism-related charges in his home country aren't likely to apply to Canada's Omar Khadr, who's been held at the U.S. detention centre in Cuba for nearly five years, Pentagon officials and defence lawyers said Thursday.

Hicks pleaded guilty to providing material support to terrorism at a military tribunal at Guantanamo Bay earlier this week. Military prosecutors have said they intend to ask for "substantially less" than the maximum 20-year jail sentence.

Omar Khadr, seen in 2002, faces charges of murder. The U.S. military alleges that he killed an American medic in a grenade attack, which wounded several other American soldiers. (Canadian Press)

In exchange for the guilty plea, Hicks will be permitted to serve whatever sentence he's given in his native Australia. Australian Prime Minister John Howard, who has been a loyal supporter of the United States in Afghanistan and Iraq, personally lobbied for Hicks to be sent home to serve his time.

Navy Cmdr. Jeffrey Gordon, a Pentagon spokesman, said Thursday it would be "pure speculation" whether other Guantanamo detainees might be allowed to serve prison sentences in their homelands.

Omar Khadr's military lawyer, Lt.-Col. Colby Vokey, said Canada had not publicly lobbied for the young Toronto man to be sent home for trial or prison, and he criticized Ottawa for not supporting its citizens in trouble abroad.

"The agreement to transfer Hicks back to Australia to serve his sentence … shows what happens when a country goes to bat for one of its own citizens," marine Lt.-Col. Vokey said in an e-mail to the Associated Press.

"The question for Omar Khadr remains: What will Canada do to protect its own citizen in Guantanamo?" Vokey asked. "What will Canada do for that citizen, especially when he was only a 15-year-old boy at the time of his capture?"

'Very serious charges': Ottawa

Khadr is accused of killing a U.S. military medic in 2002 as he was being arrested by American troops in Afghanistan.

A spokesman for the Department of Foreign Affairs in Ottawa declined to discuss whether the government would push for a deal for Khadr like the one received by the Australian detainee.

"The government of Canada sought and received assurances that Mr. Khadr is being treated humanely," said Alain Cacchione. "He faces very serious charges, but as far as serving his sentence in Canada, it is premature and speculative at this point."

U.S. law professor Muneer Ahmad, who's on Khadr's legal team, said in an editorial last month Canada has failed him by not demanding fair treatment or speaking out about the prison camp in Cuba.

"Canada is virtually alone in its silence," wrote Ahmad.

Unlike Canada, Britain refused to permit its citizens to be tried by the military commissions.

Detentions without trial criticized

No date has yet been set for his trial, but Khadr is expected to be formally charged soon with several new counts, part of several changes in the system after the U.S. Supreme Court took aim at President Bush's plan for trying suspects. 

Khadr told his family early this month that he plans to boycott his upcoming trial.

Hicks, Khadr and a Yemeni named Salim Ahmed Hamdan, who admits to being Osama bin Laden's driver, are the only three of roughly 380 men held by the United States military in highly secure cells in Guantanamo Bay to be charged with offences related to terrorism.

The U.S. had to set up a system for prosecution and tribunals after the Supreme Court ruled last June that so called "military commissions" established earlier were in defiance of the American constitution.

Amnesty International and many foreign governments — including Britain — have repeatedly criticized Washington for holding hundreds of prisoners at the Guantanamo Bay base without charge or trial.