RAISING the state pension age without taking into account regional differences in healthy life expectancy will widen inequality and disadvantage the poor, a think-tank has warned.

It claims the impact will be particularly pronounced in parts of inner Glasgow where the average healthy life expectancy is 46.7 years - almost 20 years below the current state pension age of 65.

The study by the International Longevity Centre - UK (ILC-UK) argues a large proportion of people in the most socially deprived areas are unlikely to reach state pension age in good health and would therefore be unable to work for as long as their counterparts in better-off areas.

Men in the lowest social class have a disability-free life expectancy 13.4 years lower than males in the highest social class.

In inner Glasgow, where male life expectancy at birth is 71.6, boys born in 2010 are expected to die on average 13.5 years earlier than those born in the London borough of Kensington and Chelsea, where life expectancy is 85.1.

Paul Kitson, pensions partner at PwC, said: "As this research shows, not all pensioners are equal - the better off tend to live longer than those who are not so well off. While it is clear that state pension age needs to increase, the difference in healthy life expectancy between the different socio-economic groups raises questions over whether a one-size-fits-all state pension age is the right answer."

Girls born in the London borough in 2010 can expect 12 more years of life than those in inner Glasgow. But even these figures veil vast inequalities that exist within regions, with life expectancies as low as 66 years in some of the Scottish city's most deprived areas.

The report makes a number of recommendations, including five yearly reviews of state pension age, investigating why more employed men and women are reporting a long-term health ­problem and the promotion of health improvement strategies among the socially deprived.

Baroness Greengross, chief executive of ILC-UK, said: "As we live longer lives, it appears to be a natural move to raise the state pension age. Yet as this research shows, we need to be very careful to ensure that increasing the state pension age doesn't just result in an increase in the numbers of people out of work and ineligible for state pension. Central and local government must concentrate greater effort on tacking the causes of inequalities which result in such huge divergences in life expectancy."

Last year the Chancellor announced plans to increase the state pension age to 68 by the mid-2030s and to 70 at around 2060.

Ministers say the moves are necessary to ensure the system is affordable and that workers spend an average of one-third of their lives in retirement.