More than half of adults will find themselves looking after a friend or relative at some point in their lives, research suggests.

Two thirds of women and over half of men will provide 20 or more hours of care a week before the age of 75, the UK-wide study found.

Researchers at the University of York found people were more likely to become "informal" carers in their mid-30s to mid-50s.

Informal carers

66% of women will be carers Number of carers increasing by 7% a year Over 75, more men are carers Six out of 10 people will be carers by age of 70

But there were also a large number in their mid-50s to mid-70s, according to the study published in the Journal of Epidemiology and Community Health.

Six out of 10 people are likely to have looked after someone in their own household by the time they are 70.

It is often a temporary role, however, and researchers found there was a high turnover of carers.

The survey is based on information collected on more than 9,000 adults who took part in the British Household Panel Survey between 1991 and 1998.

'No option'

Dr Michael Hirst of the university's Social Policy Research Unit said that during the 1990s, the number of adults providing informal care for 20 or more hours a week increased by 7% a year.

"If this trend continues beyond the study period, increasing resources will be required to assess their needs and to support them in their caring activities," he said.

He concluded that government policies need to reflect the fact that much of the care coincides with the period before retirement and many women have no option but to give up work to take on the role of carer.

However, Dr Hirst also discovered that after the age of 75, more men are likely to be looking after someone in their family.