A suicide bomber Thursday killed up to 17 Pakistani security men when he blew himself up at a check post in northwest Pakistan's Khyber tribal agency bordering Afghanistan, a top official in the region said.

Hospital workers assist a man, injured from a suicide bomb attack, after he was brought to a hospital in Peshawar August 27, 2009. [Xinhua]

The bomber struck a group of tribal police when they were making arrangements for fasting, administrative officer Tariq Hayat said.

Reports said the suicide blast took place at the Khasadar check post in Pak-Afghan border town Torkham in Khyber near the main town Landi Kotal. The death toll is expected to rise, reports said.

Pakistan's state television and private TV channels put the death toll at 20.

Hospital workers assist a man, injured from a suicide bomb attack, after he was brought to a hospital in Peshawar August 27, 2009. [Xinhua]

Several others security men were also injured in the attack, officials said.

No group claimed responsibility for the attack. But Taliban militants in the past had attacked security men in Khyber agency.

Several extremist groups including Tehrik-e-Taliban Pakistan (TTP) are active in Khyber and NATO supplies trucks and oil containers also regularly come under attacks in the same region.