Treasurer Joe Hockey has again flagged raising the retirement age, saying people living longer is imposing costs, including the age pension, which may not be sustainable.
Mr Hockey said the coalition supported the former Labor government in lifting the retirement age from 65 to 67 by 2023.
Speaking at the start of Saturday's G20 finance minister's meeting in Sydney, he said an ageing population and longer life expectancy was common to most of the developed world, not just Australia.
"But we have also got to recognise that there are unique costs associated with that and you have got to ask if the current system is able to cope with that on a sustainable basis," he said.
Finance Minister Mathias Cormann said life expectancy was 55 when the age pension was introduced, but life expectancy was now 30 years longer.
"That does have implications for our economy and for our capacity to sustainably fund a range of services. If we want to keep spending more, at the end of the day we would have to tax more," he told Sky News.
Labor frontbencher Matt Thistlethwaite said lifting the retirement age to 67 was the right thing to do at the time.
"As to further reform, Labor will have a look at that, but at the moment we don't see the need for change," he told Sky News.
"What we are saying is there are other measures that can be taken to improve the sustainability of the budget."
Opposition families spokesman Jenny Macklin said Mr Hockey needed to spell out just what he had in mind.
"Joe Hockey must explain to Australian pensioners what his plans are for the age pension after comments yesterday left them in fear that they are going to have their pensions cut," she said in a statement.
Ms Macklin said seniors deserved absolute certainty about support they would receive in retirement.
National Seniors spokesman Michael O'Neill has said any moves to raise the pension age were problematic.