Kabul: Afghan police mistook US troops on a nighttime mission for Taliban fighters and opened fire on them, prompting US forces to return fire and call in attack aircraft, killing seven Afghan police, officials said Tuesday.

President Hamid Karzai's spokesman labeled the shooting at a remote police checkpoint in the eastern province of Nangarhar "a tragic incident" caused by a lack of communication.

"The police forces were not aware of the coalition's operation," said spokesman Karim Rahimi. "The police checkpoint in the area thought that they were the enemy, so
police opened fire on the coalition, and then the coalition thought that the enemies were firing on them, so they returned fire back."

The commander at the post, Esanullah, said US gunfire and helicopter rockets killed seven policemen and wounded four.

Maj. Chris Belcher, a spokesman for the US-led coalition, said a combined coalition-Afghan force was ambushed by small arms fire and rocket propelled grenades from two sides while on the way to conduct an operation against a suspected Taliban safe house.

"Afghan and coalition forces took incoming fire and they responded to it," Belcher said. The forces called in air support, he said.

A policeman at the remote checkpoint said police called out for the US forces to cease their attack.

"I thought they were Taliban, and we shouted at them to stop, but they came closer and they opened fire," said Khan Mohammad, one of the policemen at the post. "I'm very
angry. We are here to protect the Afghan government and help serve the Afghan government, but the Americans have come to kill us."