Canada's top military commander made a stunning turnaround Wednesday, contradicting testimony he made one day earlier about an Afghan detainee who was abused by Afghan police.

The move is akin to a political thundercloud breaking over the Conservative party.

During a hastily-called news conference, Gen. Walter Natynczyk said he received new information Wednesday about an incident in June 2006 when an Afghan detainee was transferred to Afghan police, then beaten.

One day earlier he testified that the man had only been questioned by Canadian troops, not detained.

He corrected that statement on Wednesday, saying the detainee had indeed been captured and held by Canadian troops before they handed him over.

The Canadians later took him back after realizing he was being abused by the Afghans.

The change in stance contradicts the Conservative government's position that there is no evidence Canadian-captured detainees were being abused prior to a new transfer agreement in 2007.

It also contradicts what Natynczyk has been saying since May 2007 about the incident.

Natynczyk said he received the field report on the actual incident only Wednesday and decided to hold a news conference as soon as the information was in his possession, in order to correct his earlier statements.

"Yesterday, just like in May '07, I provided the best information that was available to me," he told reporters. "And the moment I saw this report this morning, I realized it was wrong, or the information I provided yesterday was incorrect, and I'm responsible for that."

Natynczyk said he will be looking into why it took so long before the correct information arrived on his desk.

Government responds to critics

In question period Wednesday, Defence Minister Peter MacKay was barraged with calls from the opposition to resign following Natynczyk's revelation contradicting MacKay's previous claim that there was no evidence of abuse of Canadian-captured detainees following the 2007 transfer agreement.

"The prime minister and the defence minister can't spin their way out of this one," NDP leader Jack Layton said. "The chief of the defence staff just contradicted everything they were saying in this House time and time again."

"The Minister claimed there was no proof of abuse -- he was wrong, and he should take responsibility and resign," Layton added. "And if not, the prime minister should demand it today."

In his defence, MacKay said he only became aware of Natynczyk's new testimony Wednesday morning after speaking with the general, adding, "He immediately went on the record to correct the record."

"He did the honourable thing. I accept what he said today as the truth," said MacKay, before he appeared at a Commons committee examining the issue.

Speaking in French, Prime Minister Stephen Harper went on the offensive, accusing the opposition of lacking support for Canadian troops.

"It's the opposition who is accusing our soldiers of committing war crimes -- not this government," he said. "This government has defended, in all cases, our Canadian soldiers' actions."

In response, Liberal Leader Michael Ignatieff accused the Conservatives of avoiding the main issue.

"General Natynczyk did the right thing. Our soldiers on the ground did the right thing. The issue is whether the government -- the government -- did the right thing," he said.

The issue has been on top of the agenda in Ottawa and in question period in the House of Commons since diplomat Richard Colvin went public with allegations about torture.

Colvin claims to have issued multiple warnings to the government in 2006 about possible prisoner torture and abuse at the hands of Afghan captors -- and says little or nothing was done about it.

The Conservative government quickly slammed the diplomat, dismissing his claims and pointing to a number of top military officers who disagreed with the diplomat's allegations.

On Wednesday, Ignatieff repeated opposition demands for a public inquiry into the issue. So far the Conservatives have rejected the possibility of an inquiry.

"Canada is proud of its human rights record. We're proud of our Geneva Conventions record. We're proud of our forces. But we need a judge to say 'okay, let's look at the whole track record, the whole period, and make sure we get this right,' because the honour of our country, the honour of armed forces is at stake," Ignatieff said.

"It's time to stop this nonsense and get a judge to sort it out."

The NDP also held a news conference immediately following Natynczyk's statement. NDP foreign affairs critic Paul Dewar said the top soldier has "fully exonerated" Colvin with his recent comments, and that the Conservative government's position on the matter is now reduced "to shreds."