Canada's pension system is more sustainable than some people believe, a public policy expert said Tuesday as members of Parliament bickered over pension reform and cutbacks.

Jack Mintz, head of the public policy school at the University of Calgary who authored a report on retirement income adequacy, told CTV's Power Play Tuesday that Canada's pension programs are relatively solid and better than those in many European countries.

Earlier in the day, MPs got into a heated debate over Old Age Security after returning from a six-week break Monday.

Debate over a piece of legislation that would create new pooled pension plans became a venue Tuesday for opposition MPs to criticize the Conservative government's plans to reform OAS -- although the two are far different, with OAS available to everyone who has lived in Canada.

"Seniors are worried about their future, but they are also worried about the future of their children and their grandchildren," interim NDP Leader Nicole Turmel said Tuesday. "Our seniors have worked hard to give a better life for future generations."

In a speech last week to a gathering in Davos, Switzerland, Prime Minister Stephen Harper said OAS, in its present form, is unsustainable in the longer term. Sources told CTV News the government is considering raising the retirement age to 67 from 65.

The government says OAS will cost $108 billion by 2030, up from $36.5 billion today.

But critics say Harper is ignoring an important fact – the economy will also grow over that 20 year period.

While Harper has since insisted that no immediate changes are coming and current seniors "will not lose a penny," he was ambiguous about future OAS reforms.

Meanwhile, the majority of Conservatives voted Tuesday to limit debate on second reading of Bill C-25 -- the pooled pension plan legislation -- to two more days.

While raising the retirement age would help reduce government expenses, Mintz said Canada's age-related expenditures are much bigger than pension costs. They also include health care and long-term care, which eat up a lot of the budget – and continue to increase.

It's "the overall package," not just the cost of pension plans that's been a big concern for both federal and provincial governments, Mintz said.

While low-income Canadians are "well-taken care of" by various social assistance programs once they reach retirement, it's the "modest income crew" – as Mintz calls the group – that struggles in senior age, he said.

However, it's important to remember that even those who don't have comfortable pension savings still may have other assets, such as real estate and businesses, Mintz said.

Overall, Canadians' retirement prospects are "not as negative as it's often painted," he said.

Adding to the confusion is the fact that many Canadians – particularly younger ones -- don't know the difference between OAS and the Canada Pension Plan, which all workers contribute to. Regardless, everyone needs to seriously think about saving for retirement, experts say.

Harper is not the first prime minister who tried to reform the pension system. Former prime ministers Brian Mulroney and Jean Chretien also attempted reforms during their time in office.

With files from The Canadian Press