Militants destroy 27 Nato oil tankers in southern Pakistan after supply route to Afghanistan closed

Suspected militants in southern Pakistan have destroyed at least 27 tankers carrying fuel for foreign troops in Afghanistan.

The incident came the day after the Pakistan government blocked supply routes to its neighbour in an apparent protest at a Nato air raid which killed three Pakistani troops.

The convoy of tankers attacked on Friday is believed to have been heading to a second crossing in the southwest of the country which was still open. It is not yet clear if the vehicles had been diverted because of the border closure.

Attack: At least 27 tankers carrying fuel for foreign troops in Afghanistan were destroyed in southern Pakistan on Friday morning

Border: Pakistan closed the crossing in an apparent protest at a Nato air raid which killed three Pakistani troops earlier this week

No-one has claimed responsibility for the raid in the southern town of Shikarpur.

The oil tankers are said to have been parked at a petrol station when they were attacked on Friday morning.

Witnesses claim up to 15 gunmen opened fire on the convoy to scare the drivers away before setting the vehicles on fire.

Around 80 percent of the fuel, spare parts, clothing and other non-lethal supplies for foreign forces in landlocked Afghanistan travel through Pakistan after arriving in the southern Arabian sea port of Karachi.

Nato has other supply routes to Afghanistan, but the Pakistani ones are seen as the cheapest and most convenient.

Attacks on coalition supply convoys are rare in central and southern Pakistan, meaning they rarely travel with an armed escort.

Pakistani security forces do though usually provide guards for the trucks and tankers in the northwest of the country.

However, local officials had warned that after two alleged Nato helicopter incursions last weekend they may stop providing protection to convoys if it happened again.

Tensions between Islamabad and Washington have become strained in recent years due to the number of innocent civilians killed by coalition forces.

Friday's attack and the decision to close to the border this week have done little to improve the uneasy relations

Pakistan said two Nato choppers fired on one of its border posts in the northwest's Kurram tribal region, killing three Pakistani soldiers on Thursday.

Nato said its helicopters entered Pakistani airspace and hit a target only after receiving ground fire. The alliance expressed condolences to the families of the soldiers and said both nations would investigate the incident.

It was the third alleged incursion by Nato helicopters into the northwest in the last week.

Vulnerable: Attacks on coalition supply convoys are rare in central and southern Pakistan, meaning they rarely travel with an armed escort

Militants: Witnesses claim up to 15 gunmen opened fire on the convoy to scare the drivers away before setting the vehicles on fire

Destroyed: The incident came the day after the Pakistan government blocked supply routes to Afghanistan