The rattle of gunfire on two occasions during the day reverberated around the Nahr al-Bared camp, prompting troops surrounding the coastal shantytown to fire shells toward the northern and eastern entrances where the Islamists are holed up, AFP correspondents said.

Smoke was seen billowing from the area, the epicentre of the fighting between the army and fighters from the Sunni Muslim extremist group Fatah al-Islam, but calm later returned.

Hundreds of heavily armed soldiers, backed by tanks, armoured personnel carriers and machinegun-mounted jeeps, surround the north Lebanon camp where several thousand civilians remain trapped without running water, with little food and no electricity.

As the siege entered its eighth day, political tensions were rising because of divisions over how to handle the crisis and a UN vote this week on the creation of a court to try suspects in the murder of ex-premier Rafiq Hariri.

Hariri was killed in a massive Beirut bomb blast in 2005 widely blamed on former powerbroker Syria, which was later forced to end nearly 30 years of military and political domination of Lebanon.

Lebanon's Western-backed ruling majority has accused Syria of stirring the troubles in the north and blamed it for a string of recent bomb attacks in a bid to block the tribunal. Damascus has denied the allegations.

Troops have kept Nahr al-Bared under siege since Fatah al-Islam attacked army targets on May 20, sparking fierce gunbattles in the camp and the nearby port city of Tripoli which have left 78 people dead.

According to UN estimates, between 3,000 and 8,000 of the 31,000 Palestinian refugees registered at Nahr al-Bared are still inside the camp, while Prime Minister Fuad Siniora said on Sunday that 5,000 remained.