Lebanese security forces seized a car loaded with explosives and arrested four men suspected of preparing bombs, days after a deadly bombing in southern Beirut, security sources said yesterday.

The car was discovered on Saturday about 15 kilometres south of the capital in Naameh, laden with five containers of TNT as well as nitroglycerin, they said.

The four men were being held on suspicion of preparing explosives for possible use in car bombings, but were not believed to be connected to Saturday’s discovery or to the car bomb that killed 27 people three days ago, the sources said.

That attack in a Shi’ite district of southern Beirut, which is a stronghold of the Lebanese militant group Hizbollah, was the deadliest in the capital since Lebanon’s 1975-1990 civil war. The bombing, which Shi’ite Hizbollah blamed on radical Sunni Muslims, followed months of growing sectarian tension in Lebanon fuelled in part by Hizbollah’s intervention against Sunni Muslim rebels in Syria’s civil war.

The two-year conflict inside Syria has spread across the Lebanese border, with rocket attacks in the Bekaa Valley, street fighting in the Mediterranean cities of Sidon and Tripoli and bombs in Beirut.

Yesterday four rockets were fired from Syrian territory towards the Shi’ite town of Hermel in the Bekaa Valley, security sources said. The rockets landed near to the town but there were no reports of casualties, they said.

Security forces at checkpoints on the main coastal road to Beirut from southern Lebanon were stopping and searching vehicles on Sunday, drivers said.