Militants destroyed at least 34 trucks in a rocket attack Thursday on a NATO trucking terminal in southwest Pakistan supplying troops in neighbouring Afghanistan, police said.

Some 44 oil tankers and goods trucks were parked in the temporary terminal in Quetta after Pakistan shut down supply lines for NATO forces in anger at a deadly cross-border air strike which killed 24 Pakistani soldiers.

Quetta police chief Ahsan Mehboob said only two trucks remained unaffected by the gun and rocket attack which triggered the fire while eight other vehicles were partially damaged.

There were no casualties in the attack, he added.

Senior police official Malik Arshad earlier told AFP that gunmen fired bullets and a rocket at the NATO oil tankers and the ensuing blaze engulfed more than 20 vehicles in Quetta, capital of the southwestern province of Baluchistan.

"Flames were rising from more than 20 vehicles. We do not know about any casualties yet because the blaze is still so huge," Arshad said.

"First the fire started in two oil tankers and the fuel started leaking which spread the fire to other vehicles," Arshad said.

"Fire brigade and emergency services were called in immediately after the attack."

Paramilitary soldiers cordoned off the site as firefighters battled the massive blaze, with flames shooting high into the night sky and thick black smoke billowing from the burning trucks.

The terminal is one of three set up in and around Quetta for the stranded NATO oil tankers and trucks.

No group has so far claimed responsibility for the attack but the Taliban have in the past said they carried out similar attacks to disrupt supplies for the more than 130,000 US-led international troops fighting in Afghanistan.

Taliban and Al-Qaeda-linked militants frequently launch attacks on NATO supply vehicles in the northwest and southwest regions of Pakistan, which border landlocked Afghanistan.

Most supplies and equipment required by foreign forces in Afghanistan are usually shipped through Pakistan, although US troops increasingly use alternative routes through Central Asia.

NATO has launched an investigation into the raid last month in which 24 Pakistani soldiers were killed.

US President Barack Obama has expressed condolences to President Asif Ali Zardari for the deaths, saying it was not a "deliberate attack."

The lethal November 26 air strike has brought the fragile Pakistani-US alliance to a fresh low.

Pakistan sealed its Afghan border to NATO supply convoys, boycotted this week's Bonn conference on the future of Afghanistan and ordered US personnel to vacate an air base reportedly used by CIA drones.

Pakistan shut its main northwestern border crossing to NATO supply vehicles for 11 days last year after a cross-border NATO helicopter assault killed two Pakistani soldiers.

Scores of NATO supply vehicles were destroyed in gun and arson attacks while that crossing was shut, as Taliban militants stepped up efforts to disrupt the route in response to US drone strikes in Pakistan's tribal belt.