The clashes Saturday night and early Sunday in the Tripoli neighbourhood of Abu Samra marked a new escalation in the army's battle with Islamic militants, as the fighting shifted from the bomb-ravaged, besieged Palestinian refugee camp of Nahr el-Bared on Tripoli's outskirts back to this city where violence first erupted May 20.

An army soldier, a policeman and two family members were killed in the confrontation, which began with troops laying siege to a building where the gunmen had taken refugee after nighttime clashes in the area, the security officials said, speaking on condition of anonymity because they were not authorised to speak to the media.

Six of the gunmen were also killed, the officials said, adding that troops stormed the building and were nearing the end of the operation.

The slain policeman happened to live in the besieged building. He confronted the gunmen, who killed him, his daughter and his uncle after failing to take the family hostage. At least 10 other people were wounded, including the policeman's wife and two relatives who were soldiers, the security officials said.