OTTAWA - The government has been crystal clear on the cost of the F-35 fighter jets, Prime Minister Stephen Harper said Sunday.

Speaking to reporters in Cartagena, Colombia, where he was attending the Summit of the Americas, Harper said the figures his government used publicly was for the acquisition of the stealth fighter.

"Other numbers cited, obviously have to do not just with the acquisition of the F-35 but operations of the F-35," he said.

"There's more than one number, there's more than one cost depending on what you're counting. These things have all been well known for some time. But in terms of our numbers, I've been very clear."

In a report released earlier this month, auditor general Michael Ferguson found National Defence officials didn't adequately inform ministers about problems with the F-35 fighter program, underestimated expected costs and bent the procurement rules.

Ferguson also pointed out defence officials had an internal estimate of $25 billion to buy and operate 65 F-35 jets over 20 years, but only presented a $16-billion figure publicly.

Following the critical report, Defence Minister Peter MacKay blamed accounting issues for the $10 billion gap.

He said the department kept the operational costs like fuel and upkeep for internal use.

-- with files from Kristy Kirkup, Daniel Proussalidis