David Cameron has called for a "profound cultural change" in the way society treats older people, warning Britain must adapt to its ageing population.
The Conservative leader said older people should be given more opportunities to work, citing figures from Age Concern suggesting the economy could be boosted by £30 million by encouraging the over-50s back into the job market.
"Retirement used to be a luxury for a lucky few - a few brief years of inactivity between work and death. But now a long life after 65 is the norm. And yet we still hold on to the idea of retirement at 65," Mr Cameron said.
"You work at full pelt right up to the wire - then you stop altogether. It doesn't make sense anymore. We need to see retirement as a process, not an event - a slope, not a cliff - then we will realise the potential of older people."
However, work and pensions secretary John Hutton warned the Tories wanted to abolish the new deal for older people, which had helped get 1.7 million over 50s into work since 1997 and said the Tory leader had no credibility.
The Liberal Democrats also accused the Conservatives of being "the block for many years to changing attitudes towards older people" in failing to consistently support age discrimination legislation.
In a speech to Age Concern today, Mr Cameron warned that older people had been "airbrushed out of the picture" but action was now needed.
The baby boom generation reached retirement age, he said, and the proportion of older people was set to rise from one in six to one in four in 30 years.
"It's time we woke up to the change that is coming. We need a quite profound cultural change - in the way we think about older people. And a revolution in social responsibility - in how we behave towards older people," Mr Cameron added.
The state of Britain's care homes highlighted society's poor attitude to older people, he said, warning many resembled "departure lounges, grey ghettoes with rows of elderly people isolated, unoccupied, just waiting to die".
There should be greater sharing of homes between older people and young families with nowhere to live, and planning authorities should mix care homes and areas with many young people, to ensure older people were not "out of sight, out of mind".
Age Concern director general Gordon Lishman welcomed the Tory leader's comments, but warned understanding was not enough: "Older people are looking for clear policies that provide long-term solutions to pensions, public services and long-term care funding."
However, work and pensions secretary John Hutton noted that the Conservatives' economic competitiveness policy group today warned the ageing of the population would become a "major factor depressing the rate of growth of GDP per head".
"John Redwood's prediction certainly would be the case if the Tories came back to power with their commitment to axe Labour's measures that are helping older people get back to work," Mr Hutton said, referring to the New Deal 50+.
He added: "His [Mr Cameron's] commitment to year on year public spending cuts shows that once again he is willing the ends without being committed to the means."