A months-long battle over the true cost of the F-35 fighter jet grew fiery Wednesday, fuelled by an auditor general's report the opposition said is so damning that somebody must step down.

Opposition MPs devoted most of question period to Auditor General Michael Ferguson's Tuesday report, which said the process to choose Canada's next generation of fighter jets, run by Department of National Defence officials, was inefficient and not managed well.

"Key decisions were made without required approvals or supporting documentation," he said in a report to Parliament.

Harper says he and the cabinet ministers in charge of the process accept their responsibilities.

"The government is taking responsibility to act on [Ferguson's] recommendations," Harper said in response to questions by NDP Leader Tom Mulcair and interim Liberal Leader Bob Rae.

"The government has not acquired these aircraft, the government has not signed a contract, the government has frozen the funds for acquisition," Harper said.

The report also shows that DND estimated the total cost of the F-35 program at $25 billion over 20 years when the decision was made internally to go forward with it in 2010. But in 2011, when DND responded to a report by Parliamentary Budget Officer Kevin Page, officials said the cost would only be $14.7 billion.

Harper said the government is putting in place more supervision over the process. He has taken responsibility away from defence officials and given it to Public Works.

In corporate world, CEO would be fired

But Rae says Harper, who has centralized control of government operations in his office, can't get away with saying a mistake worth that much money had nothing to do with the man in charge.

"Any company that made a mistake of this kind, that misled its shareholders, that misled the public, that put out a misleading prospectus, that published false figures and false documents to the tune of billions of dollars, any company that did those things would fire the CEO and replace the board of directors," Rae said.

Rae says when Defence Minister Peter MacKay and Public Works Minister Rona Ambrose announced in 2010 that the government would buy 65 F-35 fighter jets from Lockheed Martin, Liberal researchers looked at all available information about the planes. They read reports from the Congressional Budget Office in the U.S., defence analysts and European governments.

"The numbers did not add up. The numbers were not real numbers. We knew it, we said it," Rae said.

"What was Mr. Harper's answer then? He called us liars. He said we were unpatriotic."

"He cannot now pretend that he was just the piano player in the brothel who didn't have a clue as to what was really going on upstairs."

MacKay, who took no questions Tuesday after the auditor general's report was released, said the government is "injecting more accountability" into the purchase.

"We will continue now, with the guidance of Public Works, to move forward with a proper acquisition process to replace the aging CF-18 [jets]."

Billions left out of estimates

NDP military procurement critic Matthew Kellway says he wants the ministers in charge of the files to admit that they're responsible for what happened.

"They still have a lot of explaining to do for the auditor general’s report and we will keep asking them for explanations for, for example, the $10 billion that suddenly was left out of the department's estimates for the F-35," he said.

"All I can say is that it’s hard to [say], in light of all the information in the media, all the information coming out of various accountability offices in the United States, that they weren’t aware. But I think we’re left with basically a binary alternative here. Either they were aware and they deliberately misled Canadians or they weren’t aware and we have a negligence and competence issue with this government."

Chris Alexander, parliamentary secretary to MacKay, maintained the parliamentary budget office's assessments were wrong, despite the auditor general's report Tuesday showing the calculations were correct.

Alexander said the government hasn't spent the money on the jets yet and put the blame at the feet of the reporters asking him questions.

"In the media, there has been a consistent effort to mislead people, to imply that money has been spent," Alexander said. "It hasn't yet."