A security official in Pakistan stands near a burning Afghanistan-bound oil tanker (file photo).
Taliban militants have set fire to at least two NATO oil tankers in western Afghanistan, killing four people and injuring two others.
The fatalities of the attack, which was carried out in the Farah province on Thursday, were identified as those guarding the convoy.
The trucks, carrying supplies from Pakistan to the US-led forces, deployed in Afghanistan, come under frequent attacks in the latter country.
Also on Thursday, a rocket attack killed at least five civilians in the eastern Afghanistan province of Logar.
On Wednesday, 12 villagers were killed in an airstrike, conducted by US-led foreign forces, in the province of Ghor.
The United States and its allies invaded Afghanistan in 2001 as part of the so-called war on terror.
The offensive removed the Taliban from power, but years into the invasion, insecurity continues to rise across the country, despite the presence there of thousands of foreign troopers.
The war has caused record-high civilian and military casualties.