"Two armed men on a motorbike opened fire with automatic weapons on a Range Rover carrying Butrus al-Bayya, a member of the Internal Security Service," a security source told AFP.

The source said the car was hit by 18 bullets and that Bayya died at the scene.

The killing was the fifth apparently targeted murder carried out in the same way in the city since February.

On Thursday, a Lebanese soldier was killed by two masked men on motorbikes, and a day earlier a municipal worker was murdered in the same fashion.

It remains unclear if the murders are linked to chronic violence in Tripoli, where decades-long tensions has been exacerbated by the conflict in neighboring Syria.

The fighting pits the Sunni district of Bab el-Tabbaneh against neighboring Jabal Mohsen, whose residents are Alawites, like Syria's President Bashar al-Assad.

Earlier this month 27 people were killed in 13 days of violence that was sparked by a deadly attack on a Sunni man by gunmen on a motorbike after the killing of an official from a local Alawite party.

On Thursday, the government ordered the army and security forces to control the security situation in Tripoli and to seize arms caches in the city.

HH/HH