Eric Holder, the US attorney-general, announced that Omar Khadr, who was 15 when he was captured in 2002, will face the commission, although he did not say whether the case would be heard on the US mainland.

"We'll look at that matter. At this point it's one of the cases designated for commission proceeding. We will as that case proceeds see how it should be ultimately treated," Holder said.

Khadr is the only remaining westerner held at Guantanamo and has charges of murder, conspiracy and support of terrorism against him.

Holder's announcement came as Canada's supreme court began hearing an appeal by the Canadian government against a lower court ruling directing it to ask the US to repatriate Khadr.

Alleged attack

Stephen Harper, Canada's prime minister, has refused to call on the US to have Khadr sent back to his county, saying that the US legal process must play itself out.

Khadr is accused of killing a US soldier after he threw a grenade at the end of a four-hour US bombardment of an al-Qaeda compound in the eastern Afghan city of Khost.

He has claimed that he has been treated badly while in detention, first at a military camp in Bagram, Afghanistan, and later at Guantanamo.

Major Jon Jackson, the military attorney for Khadr, told Al Jazeera from Las Vegas that Khadr did not belong in front of the commission.

"Omar Khadr was 15 years old when he committed these crimes, which in all estimations are not war crimes and should not be before a military commission," he said.

"The lawyers in Canada have done an outstanding job. One of our civilian lawyers on the military commission case ... is up there for the supreme court argument. He has done an outstanding job in trying to get the government of Canada to do what they should do - and that's request repatriation of Omar Khadr."

'Poor treatment'

In an interview with Al Jazeera, Khadr's sister said that her brother had suffered a lot during his time at the US prison camp in Guantanamo.

"I am sure he has gone through a lot of hardship; more than anyone can imagine," Zeynab Khadr said in Toronto.

"He was under a lot of pressure and stress and he is being pushed to his limits... It was heartbreaking to see that they broke all his resistance."

While calling for any evidence against her brother to be presented in court, Zeynab Khadr said that she was disappointed by how the Canadian government has handled this case.

"If it had been someone who was blond, would he have been treated like this?" she said.

"Guantanamo was not good enough for Americans - no American went to Guantanamo and Europe [made] its best efforts to get all its citizens out as soon as they could and they were adults," she said, referring to Khadr’s young age when he was sent to the military jail.

Omar's father, Ahmed Said Khadr, is alleged to have been an al-Qaeda fighter and financier. He was killed during a raid by Pakistani forces in 2003.

Abdullah Khadr, one of Omar's brothers, is being held in Canada on a US extradition warrant, accused of supplying weapons to al-Qaeda, while another brother has said that the family stayed with Osama bin Laden, the head of al-Qaeda.

But "Omar identifies himself strongly with Canada," Lieutenant-Commander Bill Kuebler, his former US military lawyer, said last year.

Kuebler said that at the time of his arrest by US forces, Khadr was a "frightened, wounded, 15-year-old boy, a boy like other children wrongfully involved in armed conflict who had no business being there, who sat slumped against a bush while a battle raged around him."