Gunmen killed a NATO truck driver and burnt seven tankers carrying oil for international troops in Afghanistan on Monday.
The attack is the second of its kind in less than a week, local police officials told AFP.
The convoy was ambushed while returning to the port city Karachi from the Afghan border.
The gunmen attacked in the town of Dadar in Bolan district, southwest of Quetta, the provincial capital of Baluchistan, police said.
"Around eight gunmen approached the convoy on motorcycles in Bolan district, ordered it to stop and started firing on the tankers," senior local police official Inayat Bugti told AFP. "A driver of one of the tankers was also hit by a bullet and was killed instantly. The attackers later put the tankers on fire and escaped," he said.
No group has so far claimed responsibility for the attacks, but the Taliban have in the past said they carried out such attacks to disrupt supplies for the 140,000 US-led international troops fighting in Afghanistan.
Previously, such convoys departed from Pakistan for the Afghan border, but Pakistan shut its borders to NATO on November 26 following NATO air strikes that killed 24 Pakistani soldiers.
Relations between Islamabad and Washington were already at a low ebb prior to the incident in the wake of the US targeted assassination of Al Qaeda arch-terrorist Osama Bin Laden in Pakistan. US officials did not apprise their Pakistani counterparts fearing leaks would tip Bin Laden to the impending raid.
The November 26 incident – described as “tragic” and “fog of war” by Western officials – brought relations between the two countries to their present nadir.