Sporadic gunfire has erupted in the refugee camp in northern Lebanon, despite a truce between government forces and Palestinian fighters.

Alan Fisher, Al Jazeera's correspondent reporting from Tripoli, said that shots had been ringing out in the darkness amid unconfirmed reports of the Nahr al-Bared camp being shelled again by Lebanese forces.

The Lebanese army would not confirm whether tank had opened fire on the camp, saying it was something they were not willing to discuss in public.

The United Nations estimates that some 15,000 Palestinian are still stranded inside the battle-ravaged camp.

At least 78 people were killed in the fighting in Nahr al-Bared which lasted a week.

Deadline

Lebanon has meanwhile given Palestinian factions until the middle of the week to negotiate an end to fighting between the army and fighters of the Fatah al-Islam, the AFP news agency said.

"The authorities have given Palestinian organisations until the middle of the week" to try to negotiate a settlement in northern Lebanon, a source told AFP on Sunday.

The Lebanese army has besieged Fatah al-Islam, an al-Qaeda-linked group made up of fighters from across the region, since Saturday.

The negotiations involve the surrender of fighters from the group, the source said.

Walid Jumblatt, a leader of the ruling majority, said on Sunday: "Nobody has talked about a military solution, but we want the criminals to give themselves up."

Many civilians have fled from the Nahr al-Bared camp near Tripoli as a result of the fighting, while the US has flown further military aid into Beirut for use by the Lebanese army.

The ammunition supplies arrived a day after the leader of the Shia opposition group Hezbollah said Lebanon risked fighting a war "on behalf of the Americans".

Fatah al-Islam tape

Earlier on Saturday, Al Jazeera aired a tape featuring a speech by Fatah al-Islam's leader.

Shaker al-Abssi said: "We wish to die. We wish to die for the sake of God. If the leader is sitting at the forefront, he will set an example for his followers."

He said Fatah al-Islam would fight "the Jews, the Americans and their loyalists", an apparent reference to Lebanon's government.

On Friday, Hassan Nasrallah, secretary-general of Hezbollah, said in a televised speech that the country risked getting dragged into America's war against al-Qaeda.

He said: "The problem in the north can be solved politically and through the judiciary."

Nasrallah said accepting US help would draw more fighters into the country and potentially destabilise it.

Fuad Siniora, Lebanon's prime minister, has defended the import of military supplies from the US, saying the supplies had been offered by several countries months ago.

The US-supplied aid is a sensitive issue in Lebanon, where opposition leaders accuse the government of working to Washington's agenda.

Palestinian factions have been seeking a negotiated solution to end the siege and avert a battle between the Lebanese army and Fatah al-Islam.

'There is optimism'

Osama Hamdan, Hamas's representative in Lebanon, said that "as long as we agree on the necessity of a solution and we speak with a language of solution, then there is optimism".

Elias Murr, Lebanon's defence minister, said on Friday he was "leaving room for political negotiations", which he said must lead to the surrender of the Fatah al-Islam fighters.

He said: "If the political negotiations fail, I leave it to the military command to do what is necessary."

The UN has called for the protection of thousands of civilians trapped by the Lebanese army's siege of the camp.

About half of Nahr el-Bared's 31,000 residents fled the camp during an earlier truce, seeking shelter in the nearby Beddawi camp.

PHOTO CAPTION

Lebanese soldiers scan the streets as they patrol in Tripoli. (AFP)