(CNN) -- A study published Wednesday in the New England Journal of Medicine estimates that 151,000 Iraqis died of violent causes between March 2003, when the war began, and June 2006.

An Iraqi mourner carries the coffin of a relative killed by a car bomb in Baghdad.

This is much lower than a national survey published in the Lancet journal that put the number during the same period at more than 600,000, but higher than the figures compiled from media reports by the Iraq Body Count, which registered more than 47,000 deaths, the study said.

"Although the estimated range is substantially lower than a recent survey-based estimate, it nonetheless points to a massive death toll, only one of many health and human consequences of an ongoing humanitarian crisis," the study said, referring to the large numbers in the Lancet report.

The World Health Organization provided technical assistance for the journal survey, and interviewers were employees of Iraq's Health Ministry. The study was paid for by the U.N. Development Group Iraq Trust Fund, the WHO and the European Commission. The study, which also included a mental health survey, cost $1.6 million.

The estimate, part of a larger survey of family health in the war-torn country, was gleaned from interviews conducted in 9,345 households in nearly 1,000 neighborhoods and villages.

"Assessment of the death toll in conflict situations is extremely difficult and household survey results have to be interpreted with caution," said study co-author Mohamed Ali, a WHO statistician quoted in a WHO news release about the study. "However, in the absence of comprehensive death registration and hospital reporting, household surveys are the best we can do."

Violence became a "leading cause of death for Iraqi adults and was the main cause of death in men between the ages of 15 and 59 years during the first three years after the 2003 invasion," the study said.

The study indicated that "on average, 128 Iraqis per day died of violent causes in the first year following the invasion" and that the daily average violent death toll was 115 in the second year and 126 in the third year. More than half of the violent deaths occurred in Baghdad. Before the war started, from January 2002 to March 2003, about a half-dozen violent deaths were reported daily, the study said.

WHO makes reference to the Lancet study conducted by Johns Hopkins University and Baghdad's University and published in October 2006. The organization said that involved 1,849 households in 47 clusters, a lower number of samples than the new study.

It also refers to the Iraq Body Count, saying it "is likely to underestimate violent deaths "because a substantial number" don't show up in the media being monitored. At the same time, it says "trends seen in the Iraq Body Count figures are consistent with those observed in our survey."

In the WHO/Iraqi Health Ministry study, violent deaths are considered "intentional" or attributable to "armed conflict." Suicides, road accident deaths and unintentional deaths are not included.

The authors of the latest study indicate that there probably is underreporting in the study because of population movement, inherent errors posed by dealing with samples, and inability to visit some households because of security problems. E-mail to a friend

CNN's Miriam Falco contributed to this report.

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