The Nahr al-Bared camp, located near the outskirts of this northern Lebanon port city, was calm Sunday after sporadic gunfire overnight between the army and Fatah Islam militants inside punctured a four-day-old truce.

Hoda al-Turk, a spokeswoman for UN Relief and Works Agency for Palestinian Refugees, known as UNRWA, said more 5,000 refugee families or about 25,000 refugees have left the camp since the fighting began one week ago. The camp is home to about 31,000 people.

A majority of the families have fled to the nearby Beddawi refugee camp, while others are staying in Tripoli and other villages, she said.

In a videotape obtained Saturday by AP Television News in Tripoli, the head of the Fatah Islam, Shaker Youssef al-Absi, said his fighters would not surrender but would kill those who storm the camp.

"We wish to die for the sake of God ... Sunni people are the spearhead against the Zionist Americans," said the bearded leader, who is suspected of having ties to al-Qaeda. He was shown seated before a black banner, as another militant holding a machine gun stood next to him. The tape also showed militants training in an unidentified camp.

The Lebanese government has vowed to crush the militants. The military has rolled more troops around the camp, which is already ringed by hundreds of soldiers, backed by artillery and tanks. Fatah Islam has claimed to have more than 500 fighters with automatic weapons, mortars and rocket-propelled grenades, inside the camp.

Three US transport planes carrying military aid arrived from Kuwait on Saturday in an effort to help shore up the army. So far, eight military transport planes have landed at Beirut airport since Thursday four from the US Air Force, two from the United Arab Emirates and two from Jordan. Media reports said the planes carried ammunition, body armour, helmets and night-vision equipment.