The latest study of Iraqi war dead from the 2003 invasion until 2011 concludes the death toll reached half a million.
University researchers from the US, Canada and Iraq based their estimate on randomised surveys of 2,000 households.
The toll includes not only violent deaths from the invasion and subsequent insurgency, but avoidable fatalities linked to infrastructure collapse.
It exceeds the 112,000 violent civilian deaths reported by Iraq Body Count.
The British-based organisation bases its tally on media reports, hospital and mortuary records, and information from official and non-governmental sources.
There has been a surge in sectarian violence in Iraq in the past year, with almost 5,000 civilians killed in attacks between January and September, according the UN. It says more than 3,000 people died in 2012.
...The study - by researchers from the University of Washington, Johns Hopkins University, Simon Fraser University and Mustansiriya University - covers March 2003 until June 2011, six months before the US withdrawal.
...The study concludes that more than 60% of the estimated 461,000 excess deaths were directly attributable to violence, with the rest associated with the collapse of infrastructure and other indirect causes. These include the failures of health, sanitation, transportation, communication and other systems.
The most common causes of non-violent deaths linked to the war were heart attacks or cardiovascular conditions, followed by infant or childhood deaths other than injuries, chronic illnesses and cancer.
"In a war situation, people can't leave their homes to get medical care. When they do leave their homes to get medical care, they arrive at institutions overwhelmed with violent injuries," Amy Hagopian, associate professor of Global Health at the University of Washington and lead author of the paper, told NBC News.