Afghan President Hamid Karzai called Sunday on the U.S. military to avoid operations that kill civilians, saying it was his “last warning” to Washington after 14 people allegedly died in an air strike.

Reacting to the alleged deaths of 10 children, two women and two men in an air strike on Saturday Helmand province, Mr. Karzai said such incidents were “murdering of Afghanistan's children and women”.

“The President called this incident a great mistake and the murdering of Afghanistan's children and women, and on behalf of the Afghan people gives his last warning to the U.S. troops and U.S. officials in this regard,” said his office, adding that he “strongly condemned” the killings.

Adopting an unusually angry tone, Mr. Karzai said the U.S.-led operations were “arbitrary” and unnecessary”.

Local authorities in Helmand said U.S. Marines called in air support after their base in Nawzad district came under attack from small arms fire. “During the air strike, two civilian houses were targeted which killed 14 civilians and six others were wounded,” said the provincial administration.

The NATO-led International Security Assistance Force said it was investigating the allegations.

Aslam, a local elder of Nawzad district, said some shots were fired at ISAF helicopters which flew into the area, adding that the choppers returned after 10 to 20 minutes and fired rockets, killing the “innocent civilians”.

Separately the Governor of Nuristan on Sunday told AFP that 18 civilians and 20 police were killed by “friendly fire” during U.S.-led air strikes against insurgents in his troubled northeastern province.

Nuristan was the scene of heavy battles last week between the Taliban and Afghan security forces. The police and civilians were targeted on Wednesday after they were mistaken for militants, said Jamaluddin Badr.

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