The cost of Australia's new Joint Strike Fighter jets is expected to blow out by $100 million as a result of Canada pulling out of the troubled program.

Canada's newly elected prime minister Justin Trudeau has pledged to not proceed with plans to buy 65 F-35A jets, but to instead open a new tender to find a replacement for his country's aging CF-18s.

At a congressional hearing in Washington, the head of the JSF program, US Air Force Lieutenant General Chris Bogdan, warned that would push up the cost for other nations.

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"If there are 65 less A-model airplanes in that production profile from any country, whether it be Canada or someone else, we have estimated that the increase in price for everyone else is about 0.7 to 1 per cent," Lieutenant General Bogdan told the House Armed Services Committee.

"For an A-model today that's about $US1 million a copy."

In Australia this would translate to a cost blowout of almost $100 million, because the Federal Government has committed to purchasing another 70 new Joint Strike Fighters.

On Wednesday evening Defence Force officials told a Senate Estimates hearing the total budget for the F-35A project was $17 billion.

Canada is one of the nine countries that helped fund the jets' development.

Lieutenant Bogdan said Canada's withdrawal would raise the cost of a follow-on development program for the other partners because it was currently slated to cover about 2 per cent of that cost.

Andrew Davies, from the Australian Strategic Policy Institute, said Canada's expected departure was a blow to the project.

"For the program overall we're talking 65 aircraft out of 2,500 so it's not a big percentage impact but it's not great news for the program, there's no two ways about that," he said.

"One of the fundamental selling points of the Joint Strike Fighter program was multinational by giving economy of scale for everyone and also interoperability between the United States and its various allies. So you take a hit on both if one of the major partners pulls out."

The Defence Department has been approached for comment.