OTTAWA - A House of Commons committee investigating what the federal government may have known about possible prisoner torture in Afghan jails ran into a brick wall Wednesday, with the military's top lawyer refusing to answer questions.

Brig.-Gen. Ken Watkins, the military judge advocate general, claimed solicitor-client privilege about whether he'd seen warnings from a diplomat in Kandahar and whether he'd received direction from the prime minister's office.

"Obviously the coverup continues," said Liberal defence critic Ujjal Dosanjh.

"It is not part of solicitor-client privilege to hide who instructs you or who your client is. If the (Prime Minister's Office or Privy Council Office) instructed these individuals, we ought to know."

Watkins' office was copied on reports written by diplomat Richard Colvin in 2006, which laid out stark warnings about possible torture in Kandahar jails. Senior members of the Conservative cabinet say they never saw the reports.

The judge advocate general has the power to order military police to conduct an investigation if wrongdoing is suspected.

Watkins refused to say whether he -- or anyone else in his office -- saw Colvin's reports.

Colvin was the political officer at the Canadian-run provincial reconstruction base in mid-2006 when Canadian troops began handing over prisoners to Afghan authorities.

New Democrat defence critic Jack Harris said the military's top lawyer had a duty to act, if such startling information was before him.

"He should tell us and he should be able to tell us if he became aware of allegations," Harris said.

Watkins refused to say whether he'd seen published annual reports from the Foreign Affairs Department that detail Afghanistan's abysmal human-rights record. At one point, Watkins wouldn't even acknowledge whether he had read newspaper accounts of torture allegations.

All of it left opposition MPs fuming and Conservative members hinting that the committee's investigation had already turned into an inquisition.

"We've gotten off to a terrible start," said Bloc Quebecois defence critic Claude Bachand.

"I have the greatest respect for the House of Commons," Watkins told exasperated opposition MPs.

But he said his role before the committee was to answer questions about the legal framework governing the transfer of prisoners, not government policy.

While captured Taliban fighters are not considered prisoners under the Geneva conventions, they are accorded the same treatment, said Watkins.

Transferring prisoners, knowing that they face the possibility of torture, violates international law.

The committee also set out a list of witnesses it intends to call.

Gen. Rick Hillier, who retired as chief of defence staff last year, is among the top witnesses.

The committee said it also intends to call retired lieutenant-general Michel Gauthier, who commanded all overseas operations, and Brig.-Gen. David Fraser, the ground commander throughout much of 2006.

Defence Minister Peter MacKay and two former defence ministers -- Gordon O'Connor and Bill Graham -- are also on the witness list.

It's unclear how many of the hearings will be public.

The government has cast a blanket national-security exemption over a lot of information related to the case -- a move that effectively derailed a separate investigation by the Military Police Complaints Commission.

Robert Walsh, the Commons law clerk, cautioned MPs that they have the power to hold the government to account and shouldn't necessarily be trying to investigate the military.