Former chief of defence staff Rick Hillier called former diplomat Richard Colvin's statement that Afghan detainees were likely tortured "ludicrous," in testimony before a House of Commons special committee Wednesday.

Hillier also said the allegations that he knew about torture were "absolutely untrue" and "discredits" Colvin's testimony. He said the diplomat's 2006 reports on torture allegations would not have been handed to him when he was Canada's top soldier because the reports only contained second-hand information.

"We didn't base our work on things like reports written in May or June 2006, which said nothing about abuse, nothing about torture or anything else that would have caught my attention or indeed the attention of others," he said.

Hillier said only a few innocent farmers would have been detained by Canadian troops in error, and those innocently detained would have been freed quickly.

The retired general said most detainees were taken after attacks and they were found to have physical evidence -- such as explosive residue -- on them.

"We detained under violent actions, people trying to kill our sons and daughters," Hillier said.

Maj. Gen. David Fraser, who led troops on the ground in Kandahar, and Lt.-Gen. Michel Gauthier, also testified Wednesday and both backed Hillier's testimony, however in much less heated terms.

Hiller said he recently re-read the reports to make sure he didn't miss something three years ago.

"There was no reason based on what was in those reports for anybody to bring it to my attention," he said.

Gauthier, former head of Canada's expeditionary forces, said he first heard of the torture allegations in April 2007 from a Globe and Mail reporter. The first field reports of torture came on June 4, 2007.

Hillier said that when Canada temporarily stopped transferring detainees to Afghan authorities in 2007, it was based on substantial evidence and not on Colvin's reports.

The testimony from Canada's top former generals appear in stark contrast to that of Colvin, but opposition MPs say they cannot clear the matter without seeing Colvin's reports and other documents on the issue.

But the government has yet to agree to release the report, and there is no indication that the report will be uncensored if it is released.

Prime Minister Stephen Harper has said he will release all "legally available" documents related to the matter, and has called out opposition members for playing "petty political games."

However, Colvin's lawyer, Lori Bokenfohr, says the Justice Department has said that they do not accept the opinion that written or oral testimony before Parliament is exempt from national security provisions of the Canada Evidence Act.

Earlier, the clerk of the committee said parliamentary immunity would apply to almost all testimony.

The special committee has been probing the issue of prisoner transfers in Afghanistan, which a former diplomat has recently suggested was a topic Ottawa was repeatedly warned could lead to torture.

Colvin, now a Washington-based intelligence office, told the committee last week that it is likely all detainees handed over to Afghan authorities were tortured from 2006-2007.

Colvin, who was the former No. 2 at the Canadian embassy in Kabul, testified that he sent warnings to high-level officers and officials in Ottawa about the issue.

New charge

Harper and his cabinet ministers have insisted that they never saw Colvin's reports at the time they were filed -- though a report in Wednesday's Globe and Mail says that Colvin says he did in fact contact one cabinet minister's office.

While Colvin initially testified he was unsure if he had sent his reports to ministers, he sent a letter to the special committee on Tuesday indicating that he did send some of these reports to the office of the Minister of Foreign Affairs, according to the Globe and Mail report.

University of Ottawa law professor Amir Attaran says Defence Minister Peter MacKay -- who was serving as Canada's foreign minister throughout much of the time that Colvin was in Afghanistan -- will now be under pressure to explain why he didn't see these reports at the time.

"It's really quite a step up in the entire set of allegations. It's a big change for Peter MacKay," Attaran told CTV's Canada AM during an interview from Ottawa on Wednesday morning.

"Peter MacKay has been saying: 'Why didn't Colvin tell me? I didn't know.' And this morning it comes out that, in fact, Mr. Colvin sent his warnings about torture to the minister. We're going to have to see what the minister says about that later today, but I think he has a very, very tough road ahead of him."

Following his testimony before the committee last week, the Conservative government has attacked Colvin's credibility, despite the fact that he was promoted to work at the Canadian embassy in Washington where he is still employed today.

MacKay and other MPs have suggested Colvin's allegations of torture were based on hearsay -- though they acknowledge the government changed its policy on prisoner transfers in 2007, partly on the advice of the former diplomat.

However, a new Canadian Press Harris-Decima survey suggests Canadians are twice as likely to believe Colvin's allegations that detainees were tortured by Afghan authorities after being handed over by Canadian Forces members.

Fifty-one per cent of the 2,036 respondents in the Canadian Press Harris-Decima survey said they believed Colvin's testimony, while only 25 per cent said they believe the government's view that his claims are not credible. Additionally, 70 per cent of respondents said that it's unacceptable for Canadian soldiers to hand over prisoners if it is likely that they will be tortured.

Colvin's explosive allegations have also led opposition members to push for a public inquiry into the matter, a proposition that has also been supported by Amnesty International Canada and the B.C. Civil Liberties Association.

The House of Commons special committee has also sought to block the testimony of David Mulroney -- a senior adviser on Afghanistan at the time Colvin said he was sending reports warning of torture -- until they can secure the release of selected documents on the detainees issue.

Mulroney, who now serves as Canada's ambassador to China, is eager to have a chance to respond to the "very serious" allegations Colvin made last week.

"Some touched directly upon my work, that of my colleagues and of the government of Canada. I would welcome the opportunity to set the record straight," said Mulroney, who has flown back to Ottawa from China.

With files from The Canadian Press