The US has said it would investigate reports of a large number of civilian deaths in an airstrike and battle between the Taliban and international forces in western Afghanistan this week.
The State Department in Washington said late on Tuesday that coalition forces and the Afghan government would investigate the matter after receiving reports of civilian deaths in Farah province.
"The United States deeply regrets any injury or loss of life among innocent Afghans resulting from operations in which its forces are involved," spokesman Robert Wood said.
"We regard any loss of innocent lives as tragic and promptly provide humanitarian assistance to affected communities. We take all reports of such incidents seriously and investigate them thoroughly."
About 30 people, including civilians and several Taliban militants, were killed in the clash, the provincial governor said Tuesday.
The violence erupted Monday when Taliban militants attacked police posts in Shiwan and Gunj Abad, two villages in the Bala Bulok district, Governor Ruh-ul-Amin said.
After the militants killed three villagers and three police officers, ground forces called in a NATO airstrike.
"Around 30 Taliban and civilians were killed by ground forces and airstrikes," he said, adding that the total number of casualties remained unclear after some civilian houses were bombed.
Civilian casualties during anti-Taliban operations have become a delicate issue in Afghanistan.
President Hamid Karzai has pleaded several times with NATO forces to avoid civilian deaths during their operations and has admitted that his repeated demands have strained his relations with some Western countries that have soldiers in the country.