NDP MP Jack Harris spoke with CBC News on Tuesday. (CBC)

The federal NDP is calling on the Canadian government to prove that four Canadian soldiers who died in Afghanistan in 2006 were killed by enemy fire rather than a U.S. bomb.

NDP defence critic Jack Harris reacted Tuesday to leaked U.S. military documents suggesting the Canadians were killed by friendly fire.

He said the Canadian military must produce evidence to prove its assertion to Canadians that the soldiers were shot by insurgents.

"They deserve the truth. They deserve to know what actually happened and if there's any doubt cast by this and I think there is some doubt because those two stories cannot live together," said Harris, a member of Parliament who represents the riding of St. John's East.

One of the thousands of U.S. military documents that were posted on a website called WikiLeaks is raising questions about how a soldier from eastern Newfoundland was killed.

Warrant Officer Richard Nolan,39, died in Afghanistan in 2006. He was born in Mount Pearl, a city near St. John's

Days after his death, Canadian military officials said Nolan was one of four soldiers killed by the Taliban.

Pallbearers carry the coffin of Warrant Officer Rick Nolan into the Roman Catholic Basilica in St. John's in 2006. (CBC)

The military's Maple Leaf newsletter also said on Sept. 13, 2006, that "four soldiers were killed Sept. 3 during Operation MEDUSA, a significant combined effort between the Afghan National Security Forces, Canada and other NATO partners in the International Security Assistance Force as they fought to drive Taliban fighters from a region west of Kandahar city."

Warrant Officer Frank Mellish of P.E.I. and Nova Scotia, Sgt. Shane Stachnik of Alberta and Pte. William Cushley of Ontario were the other three soldiers who died that day.

Despite what the leaked U.S. documents say, the Canadian military is standing by its assertion that insurgents killed the four Canadian soldiers in 2006.

"There has to be further verification, not just assurances that have been made already that what we said before was in fact the truth," Harris said Tuesday.