Islamabad  - Militants attacked a truck serving Afghanistan-based NATO forces in Pakistan's Khyber tribal region on Friday, injuring five people, an official said.

A car bomb went off in Jamrud area as a truck carrying supplies for the Western troops passed the vehicle, Fida Hussain Bangash, a local administrator, said over the phone.

"Five passers-by, including a couple of schoolchildren, were wounded in the blast," Bangash said.

The container with supplies intended for the NATO troops was completely destroyed in the explosion.

The vulnerability of this key overland route has increased lately, as militants destroyed or plundered hundreds of Afghanistan-bound vehicles in recent months.

Friday's bombing came three days after militants blew up a bridge in Khyber, briefly cutting off the supply line, which is used to transport more than 75 per cent of food and military hardware for the US and NATO forces fighting Taliban in landlocked Afghanistan.

US authorities are in a process of securing other links through Central Asian states to keep the crucial supplies running. (dpa)