A joint United States and Iraqi survey says an estimated 655,000 people have died as a result of the US-led invasion of Iraq in 2003.

The research compares mortality rates in the country before and after the fall of president Saddam Hussein, and finds there has been an increase of about 500 deaths a day.

Critics have dismissed the findings because they are based on a statistical calculation, rather than an actual body count.

But the researchers, from John Hopkins University in the US, say their method is accurate and many death certificates have been provided to authenticate their figures.

The figure is considerably higher than official estimates.

The research has been published in the British medical journal, The Lancet, whose editor Richard Horton, says he is confident of its accuracy.

But the US president, George Bush, says the survey is not credible.

© NewsRoom 2006