The Conservatives will continue to use the "triple lock" to protect the basic state pension if they win the next election, David Cameron has said.
He pledged pensions would continue to rise in line with wages, prices, or by 2.5% - whichever is highest - during the 2015-2020 parliamentary term.
He said he wanted to give "peace of mind" to those who had worked hard. The PM indicated it was "the first plank of the next general election manifesto - pensions are protected".
In an interview with the Times, the prime minister said he had been able to make the commitment after taking "difficult decisions on raising the pension age".
BBC political correspondent Carole Walker said Labour and the Lib Dems were now under pressure to say if they would match the commitment.
Labour has previously said it supported the triple lock.
The triple lock was introduced by the coalition and means that, since 2010, many pensions have risen by about £15 per week overall.
Mr Cameron said: "I am determined to give people who have worked hard and done the right thing during their working lives real security and peace of mind in retirement.
"We are only able do this because we are taking the difficult decisions to tackle the deficit and put our economy back on the right path."