The rebels struck at a terminal on the outskirts of the city of Peshawar.

"More than two dozen militants entered the terminal and planted timed devices on 12 out of a total 18 fuel tankers parked at the terminal," senior police official Imtiaz Shah told AFP.

He said 11 tankers were blown up while the device planted on one of the vehicles did not explode, and that the militants shot dead two guards and two drivers who resisted them.

"Those who attacked the terminal were all militants but we don't know yet which group they belong to," Shah said.

Another senior police official, Muhammad Ejaz, said the militants fled after blowing up the tankers.

No group has claimed responsibility but the Taliban has claimed such attacks in the past. The bulk of supplies and equipment required by foreign troops in Afghanistan are shipped through Pakistan.