Pakistani security force on Thursday killed 34 militants in Khyber tribal region near the Afghan border. An army statement said that three soldiers were also killed and eight others injured during an encounter in Bara area. The army said that militants attacked the paramilitary soldiers while they were carrying out search operation in the area. No group has claimed responsibility for the attack. It is the second attack on security force in Khyber agency in four days. On Monday, clashes left 9 soldiers and 16 militants dead after the heavily-armed gunmen ambushed troops during a search operation. Militants have recently stepped up attacks on security force in Khyber agency, the main supply route for NATO forces in neighboring Afghanistan. Militants routinely attack NATO supply trucks in the region. Tehrik-e-Taliban Pakistan and another militant group Lashkar-e- Islam are active in the area. The security force have launched several operations in Khyber agency and cleared most of the areas of the militants but they are still active in several areas.