Opposition MPs are expressing outrage over the decision of a civilian-run military watchdog looking into the Afghan detainee transfer affair to go behind closed doors.

The Military Police Complaints Commission has barred journalists, government officials and the general public from sitting in on its proceedings in Ottawa until Thursday at the request of government lawyers.

The reason for the request is also being kept secret, with only a terse media advisory saying government counsel raised "security issues" with respect to some evidence.

Liberal defence critic Ujjal Dosanjh said he's not surprised about the move, calling it part of an "ongoing saga of a coverup" by the government over what and when it knew of allegations of torture of detainees transferred to Afghan custody by Canadian soldiers. NDP MP Paul Dewar called the last-minute decision to make the start of the hearings private "farcical."

The government has cited national security and public safety for the heavy redaction of thousands of documents pertaining to detainee transfers. But the opposition MPs said the latest shows the need for a full public inquiry into the affair.

"This government knows that it knew about the risk of torture," Dosanjh told CBC News in an interview Wednesday from Vancouver. "We continue to transfer detainees, and the government is at pains to keep all of that information from the public. I believe that that is why we've been saying the Military Police Complaints Commission has a very narrow jurisdiction. Even there, they're trying to actually prevent things happening in public."

The first witness scheduled to appear at the hearing is Sgt. Carol Utton, a military police officer who previously told commission investigators how an Afghan prisoner was mistreated.

The commission is investigating an allegation from Amnesty International Canada and the B.C. Civil Liberties Association. The groups say Canadian military police did not properly investigate officers responsible for directing the transfer of detainees to Afghan authorities, allegedly at the risk of torture.

On Tuesday, CBC News revealed the contents of an internal top-level government memo shared with CBC reporters that showed the Conservative government was warned last summer that working with the Afghan secret police would lead to allegations Canada condoned abuse and that Canadians could face legal liability for complicity in torture.

Government and military officials, past and present, have vehemently denied allegations by a former top diplomat that Canadian officials continued to transfer detainees into Afghan custody despite being aware of torture allegations.

The Conservatives say that after the allegations first came to light in April 2007, Canada acted quickly to fix its transfer agreement with the Afghans to include access to the prisons of the Afghan secret police and allow Canadian monitors to follow up on the condition of detainees.

With files from The Canadian Press