The crowd gathered at the Tartus and Aabudiyeh crossings leading to the Syrian province of Homs and cut off trucker routes by piling stones and other objects.

Dozens of cars, buses and trucks with Syrian number plates were seen parked on both sides of the border as their passengers waited for the roads to clear.

A Lebanese minister, Moin al-Meraabi, a member of the Future Movement headed by Sunni leader and Damascus opponent Saad al-Hariri, arrived at the scene vowing to open the way for civilian cars and buses.

"We will not allow the passage of gasoline and diesel fuel tankers, because this fuels goes to the military efforts of the regime of Bashar al-Assad," the minister told AFP.

In the northern city of Tripoli, meanwhile, "gunmen opened fire this evening on a Lebanese tanker truck suspected of transporting fuel to Syria," according to a security source.

"They opened fire on one and broke through the windshield. When the Lebanese driver didn't stop, they pursued him by car to the Beddawi area where they stopped him and beat him until they realised the truck was empty and released him."

There have have seen a series of protests in Sunni-majority areas of the Bekaa Valley of eastern Lebanon and in the north aimed at stopping the transfer of fuel to Syria.

Energy Minister Gebran Bassil, a member of Lebanon's ruling coalition led by Hezbollah which is allied with the Assad regime, defended the legal transfer of fuel supplies.

"The Syrian tanks are filled by a private company ... and not by the Zahrani oil refinery" in south Lebanon that is linked to the government ministry. "Fuel exports to Syria and abroad are imported exclusively by private companies."

He acknowledged "re-exports are taking place, but these are in accordance with commercial and administrative procedures" and said "private sector companies pay fees to the state to re-export their goods abroad."