Australians no longer trust the superannuation system to look after their long-term interests, Australia's former treasurer Peter Costello says.

Mr Costello told the ABC's 7.30 program the number of changes made to superannuation rules in recent years had damaged confidence in it.

"I think during the last government there were something like, I counted up, 33 different changes in budgets and mid-year reviews to superannuation," he said.

"People just don't trust superannuation as being a long-term vehicle anymore.

"They know the rules are going to vary from year to year.

"They're afraid to lock voluntary money into the system which is why it's running on compulsory contributions at the moment.

Mr Costello said people needed to be reassured super savings were safe.

"If you want to put money away for 20, 30 or 40 years you have to have some certainty it's going to be there when you retire, and I think the Government's got to give it some certainty," he said.

A productivity commission review into superannuation released today found, currently, most Australians had only small amounts of superannuation savings when they reached retirement age.

According to the review, about 40 per cent of people aged 64 had no superannuation savings at all and by the time people reached age 80, only 17 per cent had any remaining.