Gunmen ambushed a convoy of trucks travelling through north Lebanon towards the Syrian border on Wednesday, badly wounding a driver, a security official said.

The early morning attack occurred in the flashpoint Bab al-Tebbaneh district north of Tripoli, where gunmen and protesters frequently try to prevent tankers from entering Syria with fuel destined for President Bashar al-Assad's regime.

"Dozens of gunmen from the district of Bab al-Tebbaneh opened fire on a string of Syrian trucks headed towards Syria at around 2:00 am (2300 GMT Tuesday). One of them hurled an explosive at the trucks. One of the drivers was badly hurt," the official told AFP on condition of anonymity.

"The gunmen then held up the truck drivers and prevented them from continuing their journey to the Syrian border until the army intervened and rescued the injured driver," the official said.

He added that the attackers believed the tankers were carrying fuel although they were in fact not.

Tripoli frequently experiences Syria-related violence, with its majority Sunni population supporting the revolt against Assad, and its minority Alawite community backing the regime across the border.

Syria dominated Lebanon politically and militarily for nearly three decades until 2005.

Officially, Lebanon has adopted a policy of "disassociation" in the Syrian war, which has now entered into its third year, with more than 70,000 people killed according to the United Nations.