The government isn't looking to replace its diesel-electric submarine fleet with nuclear subs, Defence Minister Peter MacKay said Friday.

In an interview to air on CBC's Power & Politics at 5 p.m. ET, MacKay told Rosemary Barton that he wouldn't advise his cabinet colleagues that Canada needs nuclear subs.

"We don't live in an ideal world, so we’re not considering it," he said.

MacKay hinted earlier this week that Canada's current sub fleet might be replaced with nuclear submarines that could patrol under the Arctic ice, something the existing diesel-electric subs cannot do.

Outside the Commons, MacKay told CBC News the government is anxious to have its submarine fleet fully operational as soon as possible, providing a “very important capability for the Canadian Forces.”

But asked whether the government might look at other subs, MacKay said: “Well, there was a position taken some time ago to go with diesel-electric.

“But you know, in an ideal world, I know nuclear subs are what's needed under deep water, deep ice.”

Earlier Friday, in response to a question from an NDP MP, Government House Leader Peter Van Loan said there is "no plan to replace the diesel-electric fleet purchased by the Liberals."

"I think the honourable member has to be wary of relying unduly on misleading reports from the CBC. What is true is that our government is investing in the right mix and the right balance of our forces to have a naval capacity necessary to defend and protect Canada's sovereignty on all our ocean frontiers," Van Loan said.

Nuclear submarines $3B each

Nuclear submarines are hugely expensive — they start around $3 billion apiece — and it is unclear where the Harper government would find that kind of money, much less how it could justify such an enormous expenditure during a period of supposed austerity.

The last time a Canadian government seriously considered nuclear subs was in the late 1980s before then prime minister Brian Mulroney sank the whole program amid a public uproar.

A decade later, Jean Chrétien’s Liberal government bought four used diesel subs from the British navy in large part because it was seen as such a huge bargain.

The four second-hand subs the Chrétien government bought from the British navy in 1998 for $750 million were portrayed at the time as the military bargain of the century.

Instead, they have spent almost all of their time in naval repair yards, submerging Canadian taxpayers in an ocean of bills now totalling more than $1 billion and counting.

One of the subs, HMCS Chicoutimi, has been in active service of the Royal Canadian Navy exactly two days in the 13 years since it was purchased from Britain.

The Chicoutimi caught fire on its maiden voyage from the U.K. to Canada, killing one sailor and injuring a number of others.

MacKay says one of the subs will be back in the water off the west coast next spring, with the others to follow.