Iraqi civilian deaths put at 100,000
Tens of thousands of Iraqis have been killed in violence since the US-led invasion last year, according to public health experts who estimate there were 100,000 "excess deaths" in 18 months.
The US-based researchers found that the risk of death from violence in the period after the invasion was 58 times higher than before the war.
The rise in the death rate was mainly due to violence and much of it was caused by US air strikes on towns and cities, they said.
"Making conservative assumptions, we think that about 100,000 excess deaths or more have happened since the 2003 invasion of Iraq," said Les Roberts of the Johns Hopkins Bloomberg School of Public Health in a report published online by The Lancet medical journal.
"The use of air power in areas with lots of civilians appears to be killing a lot of women and children," Mr Roberts said.
The report comes just days before the US presidential election in which the Iraq war has been a major issue.
Mortality was already high in Iraq before the war because of United Nations sanctions blocking food and medical imports.
But the researchers described their findings after the war as shocking.
The new figures are based on surveys done by the researchers in Iraq in September 2004.
They compared Iraqi deaths during 14.6 months before the invasion in March 2003 and the 17.8 months after it by conducting household surveys in randomly selected neighbourhoods.
Previous estimates based on think-tank and media sources put the Iraqi civilian death toll at up to 16,053 and military fatalities as high as 6,370.
By comparison, about 849 US military personnel were killed in combat or attacks and another 258 died in accidents or incidents not related to fighting, according to the Pentagon.
The researchers blamed air strikes for many of the civilian deaths.
"What we have evidence of is the use of air power in populated urban areas and the bad consequences of it," Roberts said.
Gilbert Burnham, who collaborated on the research, says US military action in Iraq was "very bad for Iraqi civilians".
"We were not expecting the level of deaths from violence that we found in this study and we hope this will lead to some serious discussions of how military and political aims can be achieved in a way that is not so detrimental to civilians populations," he told Reuters.
The researchers did 33 cluster surveys of 30 households each, recording the date, circumstances and cause of deaths.
Before the war the major causes of death were heart attacks, chronic disorders and accidents. That changed after the war.
Two-thirds of violent deaths in the study were reported in Fallujah, the insurgent held city 50 kilometres west of Baghdad which has been repeatedly hit by US air strikes.
"Our results need further verification and should lead to changes to reduce non-combatant deaths from air strikes," Mr Roberts added in the study.
Richard Horton, editor of The Lancet, said the research which was submitted to the journal this month had been peer-reviewed, edited and fast-tracked for publication because of its importance in the evolving security situation in Iraq.
"But these findings also raise questions for those far removed from Iraq - in the governments of the countries responsible for launching a pre-emptive war," Mr Horton said in an editorial.