Britons should have to work until they are 67 before they receive a state pension, a new report has suggested.
The higher age for payments should be introduced between 2020 and 2030, according to the Institute of Public Policy Research report.
The think tank added the government and employers must first win the public's trust before they can make the change.
Ministers say there are no plans to raise the pension age, while the Tories say incentives would be needed.
Pension rise
The report's author, Peter Robinson, said: "Raising the state pension age is vital if the UK pensions system is to remain sustainable and cope with the pressure of an ageing population."
He said the public is reluctant to accept that life expectancy is rising, and the institute's focus groups showed people wanted to retire at or before 65.
The IPPR believes that, unless there is a clear political consensus on pensions, it will be difficult to bring about change.
"One way to build a consensus on increasing the state pension age is to link it with an increase in the basic state pension," said Mr Robinson.
'Increased choice'
Minister for pension reform, Stephen Timms, said the government was "committed to achieving consensus" on pensions.
He said: "The government has no plans to raise the state pension age but welcomes giving people increased choice as they plan for their retirement."
But the Trade Unions Congress warned that "work-till-you-drop" policies would hit poor people hardest.
Conservative pensions spokesman Nigel Waterson called for more flexibility to allow those who want to work for longer to do so.
"If the government expects people to work longer, they need to provide incentives," he said.
The Pensions Commission is due to publish its final report in the autumn.
In October last year, the commission estimated that more than 12 million people in the UK were not saving enough towards their retirement.
The commission's interim report said that some mixture of higher taxes, more saving or a higher average retirement age was needed to solve the UK's pension crisis.
But the Chancellor, Gordon Brown, has said that there will have to be a cross-party consensus before any major changes to the UK pension system are made.
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