OTTAWA - A U.S. defence analyst says Canada's new fleet of stealth jet fighters will cost almost double what the Conservative government is projecting.

Winslow Wheeler, of the Centre for Defense Information in Washington, injected himself directly into the federal election by providing his estimate at a news conference on Parliament Hill.

Wheeler says the unit cost of the F-35 jet will be about $148 million per airplane -- an estimate that is in line with what the parliamentary budget officer has projected.

The government says the unit cost will be up to $75 million per jet, and has mounted repeated public attacks on the budget officer's estimate.

The untendered jet purchase is a contentious issue during the federal election campaign. The Liberals want to scrap the deal, saying it's not the way to go while the country is in deficit.

Wheeler worked for three decades on security issues for the U.S. General Accounting Office and members of the U.S. Senate.

He said the government's estimates refer to what is known as the unit recurring flyaway cost, or URF. He said the URF is not used in Washington because it doesn't include essential things needed to actually fly an aircraft.

It is not clear that Canada would get an F-35 with an actual engine at the cost the government is projecting, he said.

"It is therefore, I believe, very reasonable to expect that the parliamentary budget officer's higher estimate of $148 million per airplane -- if and when you get around to buying these things -- is by far and away the most accurate estimate. It's a complete airplane," Wheeler said.

"Nobody on this earth is going to be buying F-35s in flyable condition at $75 million a copy. That's not in the cards."

Wheeler said there should be a public audit of Canada's decision to buy the fighter jets, and he suggested the auditor general would be best placed to conduct it.

The government plans to buy the 65 high-tech fighters to replace Canada's aging fleet of CF-18 jets.

The government estimates the overall cost to taxpayers would be about $15 billion over 20 years, including maintenance costs. That estimate is based on a unit price of $75 million per plane.

On the campaign trail, Liberal Leader Michael Ignatieff has argued that the stealth fighter jets are a big-budget Tory spending priority, along with corporate tax cuts and prison expansion, that would constrain future spending on health care.

However, the Harper government has mounted a vocal defence of its cost estimates for the F-35, saying it would create billions in industrial spin-offs for Canadian aerospace companies.