(Adds U.S. military comment, background)

ASADABAD, Afghanistan, July 4 (Reuters) - Twenty-two civilians, including women and children, were killed in an air strike by U.S.-led forces on Friday in Afghanistan's eastern province of Nuristan, an official said.

The attack happened on a road in Want district while the noncombatants were traveling in two vehicles, the district chief, Zia-Ul Rahman, told reporters.

"The civilians were evacuating the district as they were told by the U.S.-led troops to do so because they wanted to launch an operation against the Taliban," he said.

"The civilians were in two vehicles when killed by the air raid," he added.

The U.S. military confirmed the mission, but said there was no report of civilian injuries. It said the strike was in response to an attack by militants against NATO-led International Security Assistance Force (ISAF) troops. "An ISAF RC-East combat outpost in Nuristan province received indirect fire from militants today. Coalition helicopter support was used to locate the militants," it said in a statement.

"The militants were moving in two vehicles when Coalition attack helicopters were used to destroy (them) killing the combatants. No reports of noncombatant injuries" were received, it added.

The incident comes amid an upsurge of violence in Afghanistan in the past two years, the bloodiest period since the overthrow of Taliban's government in 2001. The issue of civilians killed by foreign troops is a sensitive one in Afghanistan as it undermines public support for the presence of around 71,000 international troops in the country and the government of President Hamid Karzai.

In the first six months of this year, 698 civilians were killed, 255 of them by Afghan government and foreign forces. In the same period last year, a total of 430 civilians were killed, the United Nations said last week. (Reporting by Rohullah Anwari; Writing by Sayed Salahuddin; Editing by Jerry Norton)

AlertNet news is provided by