Researchers claim to have developed a new controversial `lifespan` test that can tell how long a person will live by determining the rate of ageing.
The blood test estimates how fast someone is ageing by measuring the length of microscopic structures at the ends of each chromosome called telomeres, which keep each chromosome from falling apart when cells divide, they said.

Telomeres shorten after each cell division and animal studies have shown that a high percentage of short telomeres in blood cells is associated with a shorter-than-normal life expectancy, which is why blood tests could provide a guide to ageing and life expectancy.

More than 100 Britons have already taken the revolutionary blood test to see how fast they are ageing, and which might be used in the future to indicate statistically how long they have got left to live, `The Independent` reported.

The company behind the test believes that thousands will further take the 650 pounds blood check in UK next year, and millions more worldwide will be tested by the end of the decade.

It also expects the test to be used as part of the standard medical check-up required by insurance companies, just as they now ask about family history of disease and whether someone is a smoker or obese.

"We consider that this will become as standard a medical diagnostic test as cholesterol testing is now," said Stephen Matlin, chief executive of Life Length, which is based in Madrid.

"If you look at cholesterol testing since the early 1980s, in a period of 15 years testing volume went from nothing to about 100 million a year," Matlin said.

However, some experts have warned that there is still not enough known about telomere testing to provide people with any meaningful medical advice, and one Nobel prize-winner has warned that 99 per cent of people who take the test will not gain any benefit.

"Today there are 500 million cholesterol tests a year. If we do one per cent of this, we are doing well. We hope to be testing millions of people by 2020," Matlin said.

The company plans to lower the price of the test by 20 per cent a year for the next five years so that it costs no more than about 65 pounds by 2017, bringing it within the price range of millions of new customers.