A U.S. military court is still refusing to hear Omar Khadr's challenge of his convictions in Guantanamo Bay.

The United States Court of Military Commission Review, known as the CMCR, issued an order Monday denying a motion to lift a stay in proceedings in Khadr's appeal.

His Edmonton lawyer, Nate Whitling, said that could mean years of additional delay for Khadr in his attempt to clear his name.

"This has been hanging over his head for years and he obviously wants to get it resolved," Whitling said.

The Canadian-born Khadr was captured as a wounded 15-year-old in Afghanistan in 2002 and later pleaded guilty to five war crimes — including the murder of an American special forces soldier — before a widely disparaged commission at Guantanamo Bay.

As part of a plea deal in which he gave up his right to appeal, the court sentenced him to eight more years rather than to the jury-recommended 40 years.

Khadr, who later said the deal was his only way out of the infamous American prison in Cuba, filed an appeal with the CMCR in 2013 after arriving in Canada. He argues that the offences to which he pleaded guilty were not war crimes when he allegedly committed them.

Whitling said it's ridiculous that the appeal is still in limbo years after it was filed.

Former Guantanamo Bay prisoner Omar Khadr with his Edmonton lawyer Nate Whitling. (Terry Reith/CBC)

"It's something that could never happen in Canada," he said. "It's just stunning that this court is refusing to do its job. I use the term court loosely, because this ... is not part of the judicial branch. It's a tribunal that's part of the Department of Defence."

In April, Khadr's American lawyer, Sam Morison, asked the U.S. Court of Appeals for the District of Columbia Circuit to order the military court to hear the appeal.

The U.S. government was ordered to respond and argued that Khadr, who has been released unconditionally and lives in Edmonton, has suffered no prejudice as he waits for his hearing.

A decision by the D.C. Circuit Court is still pending, but Monday's order by the military court said that it has no reason to vacate the stay.

The CMCR said Khadr's case was put on hold while civilian courts decided the case of Ali Hamza al-Bahlul. A military commission had convicted al-Bahlul in 2008 for doing media-relations work for terrorist leader Osama bin Laden, but a civilian court quashed most of his convictions in 2013.

The CMCR said the case addresses many of the same issues in Khadr's case.

"The al-Bahlul case is still pending before the United States Court of Appeals for the District of Columbia Circuit," said the order.

"We see no reason to vacate our abeyance in appellant Khadr's case until the issues in al-Bahlul are decided finally by the D.C. Circuit or the Supreme Court of the United States."