PESHAWAR: Gunmen opened fire Saturday on two trucks carrying Nato vehicles in troubled northwestern Khyber tribal agency 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.

“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 news agency 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.

Taliban and al-Qaeda-linked militants frequently launch attacks across northwestern Pakistan and the lawless tribal belt.

Pakistan is a key transit route for the Nato mission in landlocked Afghanistan.

From November 2011 to July 2012, Pakistan shut its Afghan border to overland Nato traffic after US air raids that killed 24 Pakistani troops.