Afghan officials: US-led forces killed 9 police

In a separate incident, NATO said it accidentally killed at least four Afghan civilians Saturday night. A NATO soldier also was killed in the east.

The two cases of accidental killings could further undercut popular support for the government and foreign forces operating here. President Hamid Karzai has pleaded with the U.S. and other nations fighting resurgent militants to avoid civilian casualties.

In the western province of Farah near the Iranian border, a convoy of foreign forces showed up in Anar Dara district and clashed with Afghan police, killing nine of them, said provincial Deputy Governor Younus Rasuli.

He said the foreign troops had not informed local officials they were coming, and the police thought they were enemy fighters. The two sides fought from about midnight until 4 a.m. Sunday, and the foreign forces used airstrikes, Rasuli said.

The U.S.-led coalition said it was investigating the report. It said its forces, along with Afghan troops, had retaliated in defense against "a non-uniformed hostile force."

"The combined patrol signaled their status as coalition forces, but continued to receive fire," a military statement said. "Coalition forces then returned small arms fire and engaged the enemy with precision close air support."

In eastern Paktika province, NATO's International Security Assistance Force said it killed at least four civilians Saturday night when its troops fired two mortar rounds that landed nearly half a mile short of their target. NATO said it was investigating whether three other civilians also were killed in the Barmal district.

"ISAF deeply regrets this accident, and an investigation as to the exact circumstances of this tragic event is now under way," NATO said in a statement.

The alliance said it was providing medical aid to four civilians who were wounded.