The UK state pension age is set to rise to 68 between 2037 and 2039 seven years earlier than originally proposed, the Department for Work and Pensions (DWP) announced today.
It said that demographic pressures meant it would be "irresponsible" not to make the change, and that it would place an "unfair burden" on younger generations.
The proposals are set to impact millions of people aged under 47, but will not affect those born after 5 April 1978, with the plans expected to save the government £250bn by 2045/46.
"As life expectancy continues to rise and the number of people in receipt of state pension increases, we need to ensure that we have a fair and sustainable system," secretary of state for work and pensions, David Gauke, said.
"It must be reflective of modern life and protected for future generations. These changes will give people the certainty they need to plan ahead for retirement."
The DWP explained that when the modern state pension was introduced in 1948, a 65-year-old could expect to spend 23% of their adult life receiving it, but that this had now increased to 33.6%
It said that it had accepted recommendations proposed in a report concerning the pension age by John Cridland earlier this year, and that those affected would still receive more than previous generations.
However, it is not looking to legislate until the next review in 2023 so that the latest life expectancy figures can be used, effectively leaving it to the next government to bring in the change.
There is currently a legal requirement to review state pension ages once in every parliament, and after a report from the Government Actuary's Department earlier this year recommended a rise to 70 for anyone aged 30 or under, further increases are expected.
"If life expectancy does continue to rise then the state pension, over the longer term, will be too costly to maintain without significant sacrifices elsewhere - potentially putting an undue burden on the working age population," Barnett Waddingham consultant, Malcolm McLean, said.
"It seems inevitable, particularly if the triple lock is to continue, that state pension age will have to continue to rise reaching perhaps 70 or beyond by the mid-point of the century."