HERAT, Afghanistan, Sept 24 (Reuters) - Three Afghan guards of a U.S. private security firm were killed in an ambush by Taliban insurgents in western Afghanistan and 10 had gone 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 ten of them have gone missing," Farah's police chief Abdul Rahman Sarjang told reporters. A provincial official, speaking on condition of anonymity, however told Reuters that 13 guards had died in the attack. Police chief Sarjang said 21 Taliban fighters were killed in the clash. The Taliban could not be immediately reached for comment. They have in the past rejected their losses 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 Taliban's government in 2001. And on Sunday, one NATO soldier was killed by small arms fire in eastern Afghanistan, the alliance said in a statement. Meanwhile, in Farah, tribal elders on Monday joined Afghan forces to track down two Italian soldiers who went missing from an area of neighbouring Herat and are believed to have been kidnapped. Farah lies close to the border with Iran and the Taliban have become active there in recent months. It is also used as a main route for trafficking of Afghanistan's illegal drugs. Italy has 600 troops with NATO based in the city of Herat and some 2,200 troops in all Afghanistan.
