OTTAWA — Opposition parties accused the Tory government Wednesday of delaying the release of the findings of military investigations into two incidents in which Canadian soldiers were accidentally killed by American firepower in Afghanistan.

"This is damage control, pure and simple,'' said Liberal MP Denis Coderre. "Let's call a spade a spade.''

On Tuesday, the army released the findings of a board of inquiry that blamed a lack of co-ordination among Canadian, U.S. and Afghan forces in a March 2006 battle where Pte. Robert Costall was accidentally machine-gunned by American special forces.

The inquiry report and separate military police investigation found that the U.S. commander failed to properly outline the location of forces defending Forward Operating Base Robinson, and that Canadians did not warn American troops about their movements as insurgents were trying to overrun the outpost.

The board also found that Canadian troops were not wearing infrared beacons that could have distinguished them from enemy fighters.

The Canadian inquiry report was finished and presented for approval to the chief of defence staff, Gen. Rick Hillier, on March 8, 2007, according to documents released by the military.

Military police, who conducted a separate probe to see whether Canadians soldiers should be charged, formally wrapped up their investigation on June 8, 2007, said Lt.-Col. Bud Garrett, a senior officer with the National Investigative Service.

Coderre said it's hard to believe that five months were needed to get Hillier's signature on the report and to liaise with American authorities.

But a spokeswoman for Defence Minister Gordon O'Connor said the government had no say in the process.

"We don't ever intervene in investigations,'' said Isabelle Bouchard. "We get the findings when they come through the chain of command. And even then the minister only gets an FYI.''

Cmdr. Mike Considine, a spokesman for the board of inquiry, also said there was no foot-dragging for political reasons.

"We were waiting on information coming from the U.S. investigation,'' he said. "The report had to be reviewed for national security issues, there was a legal review, the families -- both here and in the States -- had to be notified.''

Considine said National Defence has no control over the speed of the U.S. investigation and Canadian officials have been held up, particularly the military police, waiting for their U.S. counterparts.

But NDP defence critic Dawn Black said she doesn't buy the explanation because the U.S. report into Costall's death was released a month ago in response to a freedom of information request by The Associated Press.

Releasing the Canadian findings in the middle of summer, when many are on holiday, virtually guarantees that the matter will be forgotten and swept under the rug, she said.

"It would work better for the government if they were more straightforward with members of Parliament and the Canadian public,'' she said.

"When information is held back -- rightly or wrongly -- it leads to a perception of coverup.''

Three weeks ago, late on a Friday night, the military released a report into the friendly-fire incident in which one Canadian soldier was killed and 30 others wounded after an American A-10A attack plane accidentally strafed members of the Royal Canadian Regiment at Ma'sum Ghar.

Since Canadian troops first arrived in Afghanistan, troops have been on the receiving end of accidental American fire three times.

In April 2002, four members of the 3rd Battalion of Princess Patricia's Canadian Light Infantry were killed after being mistakenly bombed by a U.S. F-16 during a nighttime training exercise near Kandahar Airfield.

The incident and subsequent investigation by the U.S. Air Force caused a political backlash in Canada.