But humans' increasing longevity could have a big impact on health budgets.

The report by the Commerce Department's Census Bureau found that countries around the world are having to confront the health problems associated with ageing.

It says: "While the pace of ageing varies, all nations are, or soon will be, facing important issues regarding health care for their expanding older populations.

"Most issues will affect elderly women, who greatly outnumber elderly men in most nations."

The report says that, in more than half of all developed countries, life expectancy for women is at least 80, some seven years more than men.

In developing countries, half of all girls will live until they are 70, but less than a third of men will reach the same age.

Increasing education

The report says it is likely life expectancy for women will rise even further because of increasing educational achievements which boost their incomes.

Japan and Australia currently have one of the highest life expectancies rates, with women born now expected to live to be 83 and men expected to survive until they are 77.

In the US, women are likely to live until they are 79.6 years old and men until they are 74.8 years old.

In the UK, the average woman lives until she is 80.1 years old with men trailing at 74.8 years.

However, in developing countries the picture is very different.

In Mali, women can only expect to live until they are 48 and men until they are 45.7 years old.

In some African countries, Aids has had a huge impact on average life expectancy. In Zimbabwe, it is likely to be cut from 61 to 39 by 2010.

The report does not suggest what governments should do to deal with the growing ageing population.

However, it notes that the World Health Organisation has called for more research into ways of dealing with illnesses associated with old age, such as osteoporosis, heart disease and dementia.

These could include screening programmes as well as new treatments.