An AFP correspondent near the camp said the artillery unit began heavy shelling early on Saturday after a largely quiet night, which had been interrupted only by the occasional crackle of light-arms fire.

Clouds of smoke and flames from several fires could be seen rising over the northern sector of the Nahr al-Bared camp, the stronghold of the Fatah al-Islam extremists.

The sustained attack followed a military statement late on Friday in which the army vowed to continue to "expand the zone under its control in the camp and to paralyse the movements of what remains of the band of terrorists."

Around 2,000 Palestinian refugees are believed to remain in the camp which was home to 31,000 before fighting erupted on May 20, the deadliest internal violence in Lebanon since the civil war.

On Friday, four soldiers were killed and others wounded when a booby-trapped building, which they were searching collapsed on them. The deaths brought the toll in the clashes to 134 killed, including 67 troops and 50 Islamist fighters.

The army also announced it had destroyed a big ammunition depot of Fatah al-Islam, and repeated its demand that those still fighting it should surrender.