Defence Minister Peter MacKay says the Conservatives will not try to remove Richard Colvin from his post in Washington. (CBC)

The Conservatives will not try to remove Richard Colvin from his post in Washington, Defence Minister Peter MacKay says, even though they question the credibility of his testimony on Afghan prisoners.

Speaking at a news conference at the opening of the Halifax International Security Forum on Friday, MacKay was asked how the Tories could keep Colvin in his role as a senior intelligence official at the Canadian Embassy in Washington if they have issues with his evidence.

"Decisions about promotions and placement of civil servants is not a partisan exercise," MacKay told reporters. "Those are decisions that are taken internally. I think there would be outrage if the government simply started hiring and firing based on politics."

The Tories have attacked the credibility of Colvin’s testimony at a parliamentary committee meeting earlier this week.

Colvin, a former senior diplomat with Canada's mission in Afghanistan, claimed that all detainees transferred by Canadians to Afghan prisons were likely tortured by Afghan officials.

He also said that his concerns were ignored by top government officials and that the government may have tried to cover up the issue.

MacKay repeated that his criticism of Colvin is not personal but that the evidence he gave "cannot be sustained."

"I don’t believe it's credible. I don’t believe it's backed up by fact and what we have to deal with in a parliamentary hearing, as we do in a court of law, or another judicial or public inquiry, is evidence that can be substantiated.

"That evidence and the suggestion that every single Taliban prisoner that was taken into custody and turned over was tortured is simply not credible and cannot be sustained by facts."

The Tories have dismissed calls for a public inquiry into the issue.

When asked by CBC News what steps the Department of Foreign Affairs took to assess the credibility of Colvin's reports concerning torture, a spokesman said it was important to let the parliamentary committee process unfold and to consider the testimony of subsequent witnesses, who could add context to the issue, before drawing any conclusions.

"Canada has a robust monitoring regime for Canadian transferred detainees in place," Jamie Christoff said in a statement.

"From the beginning of our engagement in Kandahar in 2005, Canada has taken steps with the Afghan government to ensure that Afghanistan meets its domestic and international obligations with respect to the treatment of detainees."