NATO airstrike kills 21 civilians: Afghan government

KANDAHAR, Afghanistan (Reuters) - A NATO airstrike in southern Afghanistan has killed 21 people after an aircraft fired on civilians mistakenly thought to be insurgents, the Afghan government said on Monday.

The NATO-led International Security Assistance Force (ISAF) said in a statement civilians had been killed as they approached a joint NATO-Afghan unit in Uruzgan province on Sunday, but did not say how many.

Civilian casualties have been a major cause of friction between the Afghan government and foreign forces in Afghanistan, who have launched two big offensives in the past eight months in a bid to turn the tide of a growing Taliban-led insurgency.

"I have made it clear to our forces that we are here to protect the Afghan people and inadvertently killing or injuring civilians undermines their trust and confidence in our mission," U.S. General Stanley McChrystal, commander of foreign forces in Afghanistan, said in the ISAF statement.

Zamari Bashary, a spokesman for the Afghan Interior Ministry, said 21 civilians were killed and 11 wounded, including women and children.

"ISAF troops were suspicious that several civilian vehicles contained insurgents and bombed them," Bashary said.

Amanullah Hotak, head of the Uruzgan provincial council, told Reuters the people were traveling in three mini-buses through a pass in the Char Cheno district.

An investigation has begun, ISAF said.

The incident was not part of Operation Moshtarak, the major NATO-led offensive to clear Taliban militants out of neighboring Helmand province.

(Additional reporting by Hamid Shalizi and Sayed Salahuddin in Kabul, Writing by Bryson Hull; Editing by Paul Tait)