About 29 NATO oil tankers were set ablaze and at least two troops were injured following an attack by a dozen of gunmen early Saturday morning in a town near Quetta in southwest Pakistan's Balochistan, officials and media reports said.

Fire rages after an attack on NATO oil tankers near southwest Pakistan's Quetta, on Oct. 9, 2010. About 29 NATO oil tankers were set ablaze and at least two troops were injured following an attack by a dozen of gunmen early Saturday morning in a town near Quetta in southwest Pakistan's Balochistan, officials and media reports said. [Iqbal Hussain/Xinhua]

As many as 29 oil containers for NATO supplies were heading to Afghanistan from Karachi when some unknown gunmen opened indiscriminate fire on them in Mithri area of Bolan district in Balochistan, said an official from the paramilitary Levies Forces.

He said fire fighting crew has been called in from nearby Sibi district to bring raging blaze under control and the Levies Forces have surrounded the locality and commenced a search operation.

The pre-dawn assault on NATO supplies came two days after the United States apologized to Pakistan for a cross-border air strike that killed two Pakistani soldiers in late September.

The attack is the sixth in a row since the beginning of October. Previously, militants have torched over 100 NATO fuel-carrying containers in Shikarpur, Rawalpindi, Quetta and Nowshera.

While claiming responsibility for four of the recent attacks on NATO convoys, Pakistan Taliban said the attack is a revenge for the NATO cross-border incursions and the stepped-up U.S. drone strikes and it has threatened more such attacks unless the NATO stops cross-border fightings.