OTTAWA — The Conservative government quietly went to Federal Court last week hoping to impose limits on what a military watchdog can say in its final report into torture allegations involving Afghan prisoners.

The Military Police Complaints Commission is currently reviewing evidence and writing its report after hearings into allegations that army cops turned a blind eye to suspected abuse in Afghan jails.

Federal lawyers successfully argued in 2009 that the commission's investigation of complaints should be limited to what military police knew -- or should have known -- about possible torture of prisoners by Afghan jailers.

The Harper government went even further last week in two days of hearings and challenged the definition of what military cops could have known.

Justice Department lawyers also accused the commission of stepping "out of its narrow jurisdiction" and investigating Ottawa's policy of handing over prisoners to Afghan authorities -- something it was strictly forbidden from doing.

The government wants to exclude the testimony of diplomats and civilians who did not work for the Defence Department. It lawyers also want any documents belonging to those officials, including reports that warned of torture or documented the abuse, excluded from the commissions findings.

"They're asking the Federal Court to put a muzzle on the commission," said Paul Champ, the lawyer for both human rights groups.

"They're trying to prevent or curtail the commission's ability to speak about all of the evidence they've heard. Even while the MPCC is deliberating on the evidence they've heard, (the government) is trying to get the court to issue a judgment or an order restricting what the MPCC can say."

Lawyers for the military watchdog refused to comment because a decision on the challenge is still pending.

It is the latest battle surrounding the military watchdog, which faced repeated court challenges in its nearly four-year-old investigation.

The issue of suspected prison torture shook the Harper government to its foundations at one point, but it has largely fallen out of the public spotlight.

The commission's report is the last chance for Canadians to get a comprehensive account of what happened and Champ accused the government of preventing that account from coming to light.

Court records show federal lawyers built their case to strike civilian testimony around the argument diplomats violated the privacy of potential torture victims by passing along the information.

"So that means the information couldn't be shared with military police who might investigate their torture," Champ said. "So how could they have investigated if they were prohibited from knowing anything? It's absurd."

New Democrat foreign affairs critic Paul Dewar said the Defence Department has for years claimed that it was relying on diplomats to warn them about possible torture cases.

""What is the point of these reports in foreign affairs if they were not passed on to the Defence Department?," Dewar said Sunday.

He said it speaks to the reason opposition parties defeated the government in a contempt of Parliament motion on March 25.

"Conservatives can't run from accountability by going to court," he said.

"The buck stops with the ministers."

The military's watchdog commission's intervention filed in Federal Court said the agency hasn't put pen to paper and the government should do so before commenting.

"Some of the grounds set out in the notices of application speculate what the Commission might say in its final report," said the response, penned by commission lead counsel Ron Lunau. "There are many steps remaining to be completed within the hearing process under the National Defence Act, before any final report is completed."

The commission pointed out legislation does not limit who it can interview during investigations and that there are avenues for appeal.

"While the Federal Court said in its decision of Sept. 16, 2009 that the commission may not investigate government policy, this cannot be taken to mean that the government policy pertaining to the transfer of detainees is entirely embargoed," Lunau wrote.

"The commission may be precluded from "investigating" that government policy, but this surely does not mean the commission is precluded from knowing what that policy was, or that the subject witnesses are prohibited from talking about it."

The government's refusal to hand over documents to both the commission and a House of Commons committee sparked a crisis in December 2009 where the Liberals brought in a contempt motion that threatened to topple the Conservatives. The prime minister avoided it by shutting down Parliament during the Christmas Holidays that year.

The government eventually agreed to let an independent experts and a committee of MPs -- excluding the NDP -- to review what documents could be released. A year after the agreement, the committee has yet to release a single scrap of paper, although Bloc Quebecois leader Gilles Duceppe has given them until April 15.