Gunmen set ablaze three tankers carrying fuel supplies for Nato troops in neighbouring Afghanistan, in two separate incidents in Southwestern Pakistan on Friday, officials said.
The first incident took place in Qalat town, 160 kilometres (100 miles) South of Quetta, the capital of restive oil and gas rich Baluchistan province which borders Iran and Afghanistan.
"Three men riding a motorcycle intercepted the three tankers, threw petrol and set them on fire," local police official Lal Jan told AFP.
In the second incident, two men torched another Nato oil tanker in Mastung district, 40 kilometres (25 miles) South of Quetta and fled, Jan added.
A senior provincial government official Saeed Umrani also confirmed the incident and said there was no loss of life in the two incidents.
The latest incidents came days after gunmen set ablaze 16 Nato oil tankers in the Southwestern Dera Murad Jamali town.
Nato tankers are regularly targeted with arson attacks blamed on insurgents attempting to disrupt two key supply lines that cross Pakistan's western border bound for foreign troops fighting in neighbouring Afghanistan.
In October, gunmen torched 29 oil tankers also bound for Afghanistan in the remote Mitri area, 180 kilometres (112 miles) Southeast of Quetta.
Baluchistan is torn by Islamist militancy, sectarian violence between majority Sunnis and minority Shiite Muslims, and a separatist insurgency by rebels seeking political autonomy and a greater share of profits from natural resources.
Most supplies and equipment required by foreign troops in Afghanistan are shipped through Pakistan, although US troops increasingly use alternative routes through Central Asia.