OTTAWA — Canadian Forces personnel suspended the transfer of suspected Taliban insurgents to Afghan authorities three times this year on fears the detainees were being mistreated and possibly tortured after their transfer.

The Defence Department said Monday that the suspensions were each for "a brief period of time" and lasted until Canadian authorities were satisfied that the Afghans were living up to a 2007 agreement not to torture or mistreat prisoners captured by Canadian troops fighting in Afghanistan.

The transfers of suspected insurgents were also suspended once in 2007 after that agreement had been signed, the Defence Department said.

But that new information did little to satisfy opposition politicians who continued to press the government to call a public inquiry into allegations first made last week by diplomat Richard Colvin who told a House of Commons committee that almost all those captured by Canadians in 2006 and in early 2007 were tortured after being turned over to the Afghans.

"The core of this issue is what happened between January of 2006 and the summer of 2007 when they changed the detainee regime," said Liberal Leader Michael Ignatieff. "Mr. Colvin has made clear allegations of detainee abuse in that period. What happened in that period? We believe (Defence) Minister (Peter) MacKay is now beginning to move and give us the documents we need to get to the truth."

"What the government is apparently doing now is they're dribbling out little bits and pieces of information," NDP Leader Jack Layton said.

"This underlies the importance of having a full inquiry as we proposed. Let's have a proper investigation to get to the bottom of it because otherwise there's this attitude developing globally . . . that maybe the Canadian government is covering up when it comes to the issue of human rights and torture and that's not acceptable."

Colvin, now based in Washington but, at the time, a senior Canadian official working in Afghanistan, also said he tried to alert his superiors about his concerns, with little effect.

One of those superiors was David Mulroney, now Canada's ambassador to China but then a senior foreign affairs bureaucrat. Mulroney on Monday asked a House of Commons committee probing Colvin's allegations if he could testify "to set the record straight."

Mulroney was travelling from China to Ottawa Monday evening and, if he testifies, he likely will counter Colvin's claims that his warnings about prisoner abuse were hushed up by Canadian officials.

"I encouraged officials to report freely and honestly while expecting them to meet the highest standards of accuracy, objectivity and professionalism," Mulroney said in a letter to the committee. "Canada is at the forefront of detainee monitoring in Afghanistan."

But late Monday, opposition MPs on the special committee on the Canadian mission in Afghanistan said they were not ready to take Mulroney's testimony until the government produced a raft of documents relating to the transfer of detainees.

"We never asked for him. This wasn't on our agenda," said NDP MP Paul Dewar who said he worried that, without the documents, many of which Colvin referred to in his testimony last week, Mulroney's testimony could be a "a one-sided conversation."

NDP, Liberal and Bloc Quebecois MPs on the committee — a majority of members — will require those documents be produced before Mulroney testifies.

Dewar said the committee has been seeking some of those documents for months.

The government accused the opposition of politicizing Mulroney's attempt to testify.

"We hope the opposition will stop playing political games and let Mr. Mulroney testify" said Dimitri Soudas, Prime Minister Stephen Harper's chief spokesman.

Although there is no suggestion that Canadian troops themselves tortured or mistreated Afghan detainees, under international law, Canadians could be legally liable for mistreatment by others if Canadians knew that such mistreatment was occurring after they were transferred out of Canadian custody.

"Canadian officials in Afghanistan absolutely abide by international obligations," MacKay told the House of Commons. "They absolutely abide by the Geneva Convention and they are further enabled to carry out those responsibilities because of a new enhanced transfer arrangement."

MacKay said several investigations into detainee abuse by the RCMP, by the military and by Canadian courts had not found any evidence that detainees were tortured after being transferred out of Canadian custody.

"There has never been a single proven allegation of abuse involving a prisoner transferred by the Canadian Forces. Not one," MacKay said.

MacKay has been the government's lead spokesman on the issue since Colvin's testimony, a contrast to 2007 when Harper fielded questions on allegations of detainee abuse made at that time.

Harper has yet to say anything about the issue since Colvin's explosive testimony at a Commons committee last Wednesday.

On Monday, though he was working in his Parliament Hill office during the daily question period, Harper stayed away from the House of Commons, preferring instead to a schedule a publicity photo with Canada's men's lacrosse team.

"It's significant that the prime minister was at a photo-op a hop, skip and a jump from Parliament Hill instead of being in the House responding to questions that Canadians want answered because they're questions about his leadership," said Ignatieff. "It defies belief that the most centralizing controlling prime minister in recent times should have been ignorant and unaware of the well-founded and concerning communications that Mr. Colvin sent to the government about what was happening in Afghan prisons."