Baghdad ? A new U.S. military tally puts the death toll of Iraqi civilians and security forces in the bloodiest years of the war thousands below Iraqi government figures.

The little-noticed body count is the most extensive data on Iraqi war casualties ever released by the American military. It tallied deaths of almost 77,000 Iraqis between January 2004 and August 2008 — the darkest chapter of Iraq’s sectarian warfare and the U.S. troop surge to quell it.

But the tally falls short of the estimated 85,694 deaths of civilians and security officials between January 2004 to Oct. 31, 2008, as counted last year by the Iraqi Human Rights Ministry.

Casualty figures in the U.S.-led war in Iraq have been hotly disputed because of the high political stakes in a conflict opposed by many countries and a large portion of the American public. Critics on each side of the divide accuse the other of manipulating the death toll to sway opinion.

“Even casualty rates are a political issue in Iraq,” said Samer Muscati, a Middle East and North Africa researcher for New York-based Human Rights Watch.

The new data was quietly posted on the U.S. Central Command website without explanation in July, and a spokesman at its military headquarters in Tampa, Fla., could not answer basic questions Thursday about the information, including whether it counted government-backed Sunni fighters among Iraqi security forces or insurgents among civilians.

Officials with the Iraqi Health Ministry, which tracks how Iraqis are killed through death certificates, refused to discuss the U.S. casualty data Thursday.

The figures were discovered this week during a routine check by The Associated Press for civilian and military casualty numbers that were first requested in 2005 through the Freedom of Information Act.

In all, the U.S. data tallied 76,939 Iraqi security officials and civilians killed and 121,649 wounded between January 2004 and August 2008. The count shows 3,952 American and other U.S.-allied international troops were killed over the same period.