Biting back at critics, Canada's budget watchdog maintains it's disingenuous to insist that an impending wave of retiring baby boomers is going to trigger a fiscal emergency.

"The old age demographic is not a new issue. We've known this was coming for decades," Parliamentary Budget Officer Kevin Page told CTV's Question Period Sunday.

Page has had his back against the proverbial ropes ever since his office released a sustainability report last week indicating the government can afford to enhance benefits for seniors.

The findings are at odds with Prime Minister Stephen Harper's aims to reform Canada's Old Age Security Program, suggesting the current model is unsustainable.

Though Page is tasked with providing independent analysis, his office's recent report has riled government ministers. Particularly outraged is Finance Minister Jim Flaherty who called Page "unbelievable, unreliable, incredible" in a scrum last week.

"Last February, he told the finance committee of the House of Commons that we have a fiscal deficit," a visibly tense Flaherty told reporters.

For his part, Page stands by his findings that the federal government's current system can sustain additional benefits for seniors. Waving away Flaherty's disapproval, he suggested the minister was under a lot of stress.

"I think if he follows our work over the last couple of years, he'll see it's been quite consistent," said Page, who once worked at the Federal Department of Finance.

The PBO's report acknowledges the government's burden to pay for aging seniors will rise from 14.8 per cent of program spending today to 20.9 per cent in 2030-31. Still, it concludes that the increasing cost isn't unaffordable.

Subtly laying into the Conservatives, Page urged Flaherty to release a similar report to provide parliamentarians with more insight as to why OAS benefits are at risk.

"This government in 2006 and (2007) was cutting taxes, increasing spending," he said, referring to Harper's first couple of years in office.

"All of a sudden we have a major fiscal crisis potentially headed (our way) because of an increase of recipients in old age security. I think that's a bit disingenuous."

Page, who was first appointed in 2008, suggested that his words have drawn the ire of politicians because lawmakers still aren't used to financial analysis from an arms-length agency.

"I think it's a new thing for Ottawa, I think it's a big adjustment but I think it's an adjustment that we need to get used to," he said.

Page's contract as PBO is due to expire in a year.