Relations between US and Pakistan are currently strained because of US allegations Islamabad supports Afghan insurgents. — Photo by Reuters

CHAMAN: Pakistani authorities have closed one of the two border crossings used by trucks carrying Nato war supplies into Afghanistan after a bomb hit an oil tanker.

Police officer Mohammad Tayab said the Chaman border crossing was closed ''for security reasons'' after an explosion on Thursday killed a bomb disposal expert who was trying to defuse the device.

Tayab didn't elaborate on the bombing attack.

Pakistan sometimes closes the border temporarily after attacks, though earlier this year the other, busier route in Torkham was closed for 10 days in protest against the killing of two Pakistani troops by a Nato helicopter nearby.

Relations between US and Pakistan are currently strained because of US allegations Islamabad supports Afghan insurgents.