Gunmen opened fire Saturday on two trucks carrying NATO vehicles in Pakistan's troubled northwest near the Afghan border, wounding two drivers.
The trucks came under fire in Jamrud area of Khyber, one of seven districts that make up Pakistan's semi-autonomous tribal belt, as they crossed into Pakistan from Afghanistan.
Pakistan is a key transit route for the NATO mission in landlocked Afghanistan.
"The two trailers were on their way to Karachi when gunmen attacked them at different locations in Jamrud and opened fire on them, wounding their drivers," a local intelligence official told AFP.
A senior local administration official, Jehangir Azam Wazir, confirmed the incident and said the attackers had fled.
No group has claimed responsibility for the latest attack but the Taliban have in the past said they carried out such attacks to disrupt supplies for the US-led international troops fighting in Afghanistan.
Taliban and Al-Qaeda-linked militants frequently launch attacks across northwestern Pakistan and the lawless tribal belt, which Washington has branded the most dangerous place in the world.
From November 2011 to July 2012, Pakistan shut its Afghan border to overland NATO traffic after botched US air raids that killed 24 Pakistani troops.