A prisoner leans against an entrance to the wing where political prisoners are kept at Sarposa prison in Kandahar, Afghanistan. ((Dene Moore/Canadian Press))

The Canadian government is dismissing calls for a public inquiry into the alleged torture of prisoners handed over by Canadian soldiers in Afghanistan.

Defence Minister Peter MacKay defended his government Thursday in light of allegations that detainees were routinely abused.

"There has not been a single, solitary proven allegation of abuse involving a transferred Taliban prisoner by Canadian forces," MacKay said in the House of Commons.

His comments came a day after Richard Colvin, a former senior diplomat with Canada's Afghan mission, dropped a political bombshell on Parliament, alleging that suspects handed over by Canada to Afghan authorities were tortured.

Torture warnings

Speaking Wednesday before a Commons committee on Canada's mission in Afghanistan, Colvin alleged that prisoners were turned over to Afghanistan's notorious intelligence service by the Canadian military in 2006-07 despite warnings that they would be tortured. He also suggested the federal government may have tried to cover up what was happening.

MacKay painted Colvin as having been duped by the Taliban and said Canadians are being asked to accept the word of prisoners "who throw acid in the face of schoolgirls." MacKay also said he did not know about Colvin's allegations.

However, Ottawa University law professor Amir Attaran said the onus was on MacKay to explain how he could not have known about Colvin's reports.

"The reality is that Mr. Colvin wrote 17 reports that he sent to colleagues in Ottawa. He cc's more than 70 people on those reports," Attaran said.

If Mr. Colvin was lying in those reports, "don't you think one of them would be standing up?"

Meanwhile, top Canadian officials discussed in December 2006 whether Asadullah Khalid, then governor of Kandahar, was involved in the torture of prisoners and dismissed the concern, according to The Canadian Press.

One source said the meeting was at the Privy Council Office and involved Prime Minister Stephen Harper's then-national security adviser, Margaret Bloodworth.

The revelation raises more questions about how much senior officials knew about possible Afghan prisoner abuse, what they did about it and whether they passed that information along to cabinet ministers or simply ignored it.

Opposition parties seek public inquiry

All three opposition parties attacked the Conservatives on Thursday and demanded a public inquiry.

NDP Leader Jack Layton said Canada's reputation as a champion of human rights has been hurt by the notion that prisoners handed over to Afghan authorities were tortured and that the government might have tried to cover it up.

"I believe the pressure for a full public inquiry is going to grow.… We have to clear the air here. Get to the bottom of it and find out whether we are dealing with a coverup," he told CBC News.

"We certainly have to take the appropriate actions to deal with Canada's reputation, which right now is taking a tumble."

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During his testimony, Colvin said Canada did not monitor detainee conditions; took days, weeks or months to notify the Red Cross; kept poor records; and to prevent scrutiny, the Canadian Forces leadership concealed this behind "walls of secrecy."

Richard Colvin, a former senior diplomat with Canada's mission in Afghanistan, says detainees transferred by Canadians to Afghan prisons were likely tortured. ((Chris Wattie/Reuters)) "According to our information, the likelihood is that all the Afghans we handed over were tortured," Colvin said. "For interrogators in Kandahar, it was a standard operating procedure."

Colvin worked in Kandahar for the Department of Foreign Affairs in 2006 before moving to Kabul, where he was second-in-command at the Canadian Embassy. He said his reports were ignored and he was eventually told to stop putting the reports in writing.

Speaking on CBC's Power & Politics with Evan Solomon , MacKay said Thursday a public inquiry isn't necessary because a parliamentary inquiry is already underway.

"We have a two-track forum right now in which individuals can come forward and speak about what they know," MacKay said. "But most importantly, we have a forum in which evidence can actually be questioned."

Government rejects Colvin testimony

Conservative MPs dismissed Colvin's testimony as being based on second- and third-hand information and suggested his allegations were part of a disinformation campaign.

"He had ample opportunity to speak to ministers directly. He chose not to do that. He could have spoken to Gen. Gauthier and he chose not to do that," Conservative MP Laurie Hawn said Thursday. "It's just not credible."

Retired lieutenant-general Michel Gauthier, who served as commander of the Canadian Expeditionary Force Command in Afghanistan for almost four years, told CBC News he was "deeply troubled" by Colvin's testimony.

"In my capacity as commander of CEFCOM, I very clearly understood my responsibilities under international law with respect to the handling of detainees, and I would certainly not knowingly have done anything — ever — to expose our soldiers and commanders in the field, our government, or myself to complicity in war crimes or other wrongdoing as Mr. Colvin suggests," Gauthier said.

"I look forward to providing an absolutely frank view of some key aspects of Mr. Colvin's testimony when I appear before the committee next week," Gauthier said.