ISLAMABAD: Unidentified gunmen killed at least six people and set 28 Nato oil tankers on fire carrying fuel for Nato and US forces in Afghanistan in Islamabad on Monday.

Many tankers caught fire during the attack. Rescue sources said at least six people died. The sources added that six others were injured in the attack.

A vital land route for Nato supplies for Afghanistan that has been blocked for three days will reopen "relatively quickly," Pakistan's ambassador to Washington told a US news channel on Sunday.

Pakistan halted the Nato convoys on Thursday after Nato helicopters killed three Pakistani soldiers.

"I think the supply line will be open relatively quickly," he said, adding that he expected it would take "less than a week."

"It's not a blockade. It's just a temporary suspension of the convoys moving through," Haqqani added.

Officials say nearly 70 per cent of Nato supplies and 40 per cent of its fuel requirements are shipped via Pakistan for some 160,000 US-led troops in Afghanistan.