Defence Minister Peter MacKay is defending the government's accounting of the costs of Canada's military mission in Libya, following the release of new figures by the Department of National Defence that lay out the final cost of the deployment.

The department puts the incremental costs of the mission — costs the military says would not have been incurred if Canadian Forces had not been deployed — at just under $100 million.

And the total cost of the operation — a figure that includes everything from jet fuel to pilot salaries, including the salaries of military personnel — comes in at $347 million.

Last October, MacKay told CBC Radio's The House the Libyan mission had cost taxpayers less than $50 million.

"As of Oct. 13, the figures that I've received have us well below that, somewhere under $50 million," MacKay said.

"And that's the all-up costs of the equipment that we have in the theatre, the transportation to get there, those that have been carrying out this critical mission."

Canada sent six CF-18 fighter jets and a navy frigate to Libya in 2011 to take part in international operations to enforce a United Nations no-fly zone against the forces of Moammar Gadhafi.

Government defends numbers

Defence Minister Peter MacKay, who greeted air crew members last November as they returned from the mission in Libya, is defending his previous accounting of the mission's costs. (Andrew Vaughan/Canadian Press)

MacKay faced tough questions in question period Friday over the discrepancy in costs.

"What is it this time?" demanded NDP Deputy Leader David Christopherson, "That they still can't keep their numbers straight or that they're misleading Canadians?"

Mackay insisted his numbers were accurate.

"What I said was that, as of Oct. 13, the figures that I received from the department were under $50 million," MacKay said in response.

The minister continued, "Of course, the mission went on. There were extensions ... there was, in fact, then the cost of bringing equipment and personnel home. This is incremental costing."

At an event in Edmundston, N.B., on Friday, Prime Minister Stephen Harper noted the total figure of $347 million includes the ongoing costs of operating the Canadian military, and he defended the earlier estimates.

"We always give the most up-to-date figures and it's important also to know ... that these figures include normal operations of the Canadian military, of those assets over that period," Harper said.

"All of these numbers, all of the costs of the Libya mission, were accomplished within the budget set by the government for the Department of National Defence, so this is not new money."

MacKay knew estimated cost: Vance

The director of the military's strategic joint staff was called on to explain duelling figures at a hastily-assembled news conference at National Defence headquarters on Friday afternoon.

Maj.-Gen. Jon Vance said MacKay did not mislead the public and pointed out senior military leaders referenced the figures publicly during Senate committee hearings.

But he concedes the minister would have known the estimated cost at the time and did not speculate on why MacKay chose to go with the lower figures exclusively.

Opposition parties slammed the Harper government for the confusion and compared it to the controversy surrounding the F-35 stealth fighter purchase, in which the auditor general accused National Defence of deliberately low-balling the multibillion-dollar estimate.

"Peter’s got problems with his math yet again and this government’s got problems with trying to figure out how to cost things," said NDP foreign affairs critic Paul Dewar. "I suppose he just thinks that if he can lowball it, people won’t be concerned about the costs. But, you know, in the end, the costs add up and it caught up to Mr. MacKay."

with files from The Canadian Press