WASHINGTON -- A new investigation of a U.S. air strike in August on a village in Afghanistan has found that 33 civilians were killed, far more than the U.S. military had previously acknowledged, military officials announced yesterday.

The military had originally concluded that six civilians and about 35 militants were killed. The new probe put the number of dead militants at 22.

According to the investigation, conducted by the U.S. Central Command, the civilian death toll in the Aug. 22 strike on the village of Azizabad was far lower than the 90 claimed by the United Nations and the Afghan government. Their assertions were questioned in the report, which argued that they "lack independent evidence" to support the higher death toll.

Both the first and the latest U.S. investigations concluded that the attack was a "valid military action," military officials said.

"This was a legitimate target," said a senior military official. "There is no culpability."

The higher number of civilian casualties is likely to renew questions among Afghan leaders about the U.S. military's use of force and to increase pressure to alter how airstrikes are used. But U.S. military officials are closely watching reactions to the new report in Kabul, hoping that their fuller account of the events mutes criticism.

"We are deeply saddened at the loss of innocent life in Azizabad," Army Lt. Gen. Martin Dempsey, acting head of the Central Command, said in a statement. "We go to great lengths to avoid civilian casualties in Afghanistan in all our operations, but as we have seen all too often, this ruthless enemy routinely surround themselves with innocents."

Later yesterday, Pentagon press secretary Geoff Morrell said in a statement that "although no military in history has gone to greater lengths to avoid civilian casualties, we clearly still need to operate with more care."