The Harper government is defending its $16-billion sole-sourced purchase for 65 state-of-the-art fighter jets from Lockheed Martin.

The Liberals and a former public servant who once headed the purchase project, say competitive bids should have been allowed in the purchase of the F-35 Joint Strike Fighters.

The jets will replace Canada's aging CF-18s that recently underwent a $2.6-billion upgrade. The planes will be 40 years old when they need another upgrade in 2020, so the government opted for new jets.

"We need to ensure our fighter-aircraft fleet remains the best in the world to meet the threats of the 21st century," Defence Minister Peter MacKay told a news conference featuring a prototype of the jet on Friday.

According to a Department of Defence statement, the first F-35 jet will be delivered in 2016, and the government paid $9 billion for 65 of them.

Factor in maintenance costs over 20 years and the cost rises to $16 billion.

MacKay told CTV News Channel that new military gear is good for morale, and that recruitment numbers will likely rise as the jets become operational.

"People are exited about this aircraft," he said, adding that the jets have "eye-watering capability."

But Liberal Leader Michael Ignatieff said the deal should be put on hold.

He has called for the Commons defence committee to reconvene to discuss what he says is the government's "secretive, unaccountable decision to proceed with this contract."

The Chrétien Liberal government signed a memorandum of understanding with Lockheed Martin to develop the fighter jet, but did not commit the country to purchasing the aircraft.

The public servant in charge of the military's initial involvement in the program says the current government is abusing the sole-source procedure.

"Don't get me wrong, I think the JSF is a marvelous aircraft; absolutely state-of-the-art, but there needs to be an open competition," Alan Williams, the former assistant deputy minister of material, told The Canadian Press.

The government argues the purchase will allow Canadian companies more involvement in the program in the future.

"The Joint Strike Fighter program allows Canadian companies to build on existing strengths and establish strategic capabilities," Industry Minister Tony Clement said in a statement. "Canadian companies will have direct involvement in the design of equipment in the short term, while also setting in motion opportunities for decades to come."

Liberal MP Bob Rae said that the purchase should have been announced in June, so Parliament could have discussed it in an open and accountable way.

Rae stressed that new fighter jets may be unnecessary, given the likely nature of future conflicts.

During insurgent combat or guerilla warfare, Rae said that state of the art fighter jets won't necessarily be useful.

Instead, he said the government needs to clearly map out priorities and create a long-term game plan for defence spending.

Ontario NDP MP Malcolm Allen said the defence department hasn't set out clear spending priorities since 1993.

"If we don't know what our needs are going forward, how do we know what to buy? That's a critical issue here," he said.