Suspected militants attacked and set on fire at least 20 oil tankers in Pakistan that were on their way to Nato and US troops in Afghanistan.
The attack yesterday, close to the capital Islamabad, was the third since Friday.
One of the main routes used by Afghanistan-bound trucks has been closed for days after three Pakistani troops were killed in a helicopter strike by the military alliance in a border area.
Police officer Umer Hayat said three people were killed in yesterday’s attack by “terrorists”.
The attack took place on a supply line that has been closed by Pakistani authorities in protest at the Nato helicopter attack last week.
It will raise the stakes in the closure, which has increased tensions between Washington and Islamabad but has been welcomed by Islamist groups opposed to Pakistan’s support of the US-led war in Afghanistan.
The attackers opened fire on trucks that were parked at a poorly-guarded terminal before setting them ablaze, police said.
The trucks were en route or waiting to travel to the Torkham border crossing along the Khyber Pass, which is used to bring fuel, military vehicles, spare parts, clothing and other non-lethal supplies for foreign troops in Afghanistan.
Pakistan’s other main route into landlocked Afghanistan, in Chaman in the south west, has remained open.
While Nato and the United States have alternative supply routes into Afghanistan, the Pakistani ones are the cheapest and most convenient. Most of the coalition’s non-lethal supplies are transported over Pakistani soil after being unloaded at docks in Karachi, a port city in the south.
On Friday, a day after the closure of the Khyber Pass route to Nato and US traffic, there were two attacks on oil tankers headed to the country. The convoys take several days to reach the border after setting off from Karachi and make frequent stops.
Over the past two years they often have been attacked by militants, mostly in the north western border region where militants are strongest. They also have been targeted by criminals, who can sell the clothing, vehicles and other equipment they carry.