Seventy-two militants and 11 policemen had been killed in a clash in the Western Afghan province of Farah, said a police source on Monday. \"The Public Protection Police Force (PPPF) was escorting a convoy traveling from Western Herat province to Southern Helmand province. On Sunday evening, several hundred militants launched an attack on the convoy. The clash lasted until Monday morning. The gunfight killed 72 militants and 11 PPPF police cops,\" a source of the PPPF stationed in Herat, lieutenant colonel Faird, told Xinhua. The incident took place in Chahkab area of Gulistan district just in Western part of Farah city, 695 km West of Afghan capital Kabul, he noted. The PPPF police force is in charge of providing security for convoys and development projects across the war-hit country. It replaced the local and foreign private security companies after the government dissolved private security firms in recent years. Up to 20 cops and several militants were also wounded in the clash, the sources said adding several vehicles were destroyed in the incident. The Taliban-led insurgency has been rampant since the militant group launched annual rebel offensive in April against Afghan government forces and about 98,000 NATO-led troops stationed in the country. The Taliban urged civilians to stay away from official gatherings, military convoys and centers regarded as the legitimate targets by militants. In addition, four militants were killed and five others arrested by police in Northern Badakhshan province, 315 km Northeast of Kabul, a provincial government spokesman, Abdul Maruf Raseikh said earlier on Monday.