U.S. security firm ambushed in Afghanistan

HERAT, Afghanistan (Reuters) - Three Afghan guards employed by a U.S. private security firm were killed in an ambush by Taliban insurgents in western Afghanistan and 10 were missing, officials said on Monday.

The attack on the convoy in Farah province on Sunday night was followed by a clash between the militants and the guards, officials said.

"The Taliban attacked the convoy, killed three guards of the company and 10 of them have gone missing," Farah police chief Abdul Rahman Sarjang told reporters.

A provincial official, speaking on condition of anonymity, told Reuters however that 13 guards had died in the attack.

Police chief Sarjang said 21 Taliban fighters had been killed in the clash. The Taliban could not be immediately reached for comment. They have in the past rejected casualty figures reported by Afghan and foreign troops as propaganda.

Violence has escalated in the past 19 months in Afghanistan, the bloodiest period since U.S.-led troops overthrew the Taliban government in Kabul in late 2001.

In a second bloody incident on Sunday, unknown armed men fired at a car carrying police and government officials in the northeastern province of Badakhshan, a provincial police official said on Monday.

Seven policemen and five others, including three civilian employees, were killed in the attack which he said could have been the work of a criminal group.

But a Taliban spokesman said his group had carried out the attack in a province which has been relatively secure compared to southern and eastern areas where the militants are mostly active.

Also on Sunday, one NATO soldier was killed by small arms fire in eastern Afghanistan, the alliance said in a statement.