Defence Minister Peter MacKay and two other cabinet ministers have rallied behind Ottawa's proposal to buy stealth fighter jets for up to $9 billion, while opponents questioned the need to purchase the high-tech aircraft from an American company.

MacKay appeared before the House of Commons defence committee on Wednesday and argued that choosing not to buy the F-35 Lightning II jets might leave Canadian airspace vulnerable down the road.

"This is the right plane. This is the right number. This is the right aircraft for our Canadian forces and for Canada," he said.

"If we don't make this purchase there is a real danger we'll be unable to defend our airspace, unable to exercise our sovereignty or unable to share our responsibility to both NORAD and NATO."

Ottawa has a contract to purchase 65 of the new stealth fighter jets from U.S. defence company Lockheed Martin.

Liberal MP Dominic Leblanc called the proposed purchase wasteful.

"If the government thinks that this is in fact the best and only aircraft that can meet its requirements, then surely it would win a competitive process," Leblanc told reporters.

"A competitive process would ensure that Canadians have some transparency as to value for money."

He said he believed the price would be reduced if Lockheed Martin had to compete against a similar aircraft, adding that if the Liberals form the next government they would put a hold on the contract and review the process.

Under a 20-year maintenance contract, the price tag for the deal could reach $16 billion, which would make it the most expensive procurement ever in Canada.

Leblanc added that the Harper government was failing Canadian industry by not requiring Lockheed Martin to spend money on Canadian suppliers.

However, speaking on CTV's Power Play, Industry Minister Tony Clement said Canada's aviation industry will benefit from the plan.

While there is no requirement for Lockheed Martin to ensure that Canadian companies construct components for the 65 aircraft, Clement said that domestic businesses will be allowed to bid on the global supply chain of 5,000 jets.

"It means decades of work," said Clement.

Still, New Democrat defence critic Jack Harris added to the skepticism.

Harris said he wasn't convinced the Canadian military needs stealth fighters, and he added that no contract had yet been signed, meaning the deal can still be scuttled.

"You don't need a Maserati to drive to work and you don't need a stealth, invisible jet fighter to patrol the Arctic or to patrol the East Coast of Canada," Harris told reporters after the meeting.

Alan Williams, former assistant deputy minister (materiel) with the Department of National Defence, said there's no way of knowing the government is getting the best deal without opening up the process to competing companies.

"In procurement, the perception is as important as the reality," he added. "People can start to hypothesize, why are they doing this? Because none of the public reasons make any sense."

That concern was echoed by analyst Steven Staples of the Rideau Institute, who told CTV News Channel that the government squandered negotiating leverage by announcing its intent before the deal was done.

"It's like going into a BMW dealership and saying ‘I've decided to buy a Beamer, now tell me how much I am going to have to pay?' You really give up all your negotiating ability for it."

With files from The Canadian Press