The majority of the families caught in the crossfire between Islamic militants and the Lebanese military have escaped the besieged refugee camp where the battle is taking place, the United Nations said Sunday.

However, thousands remain trapped inside the camp.

It was quiet Sunday at the Nahr al-Bared Palestinian refugee camp near Tripoli, after sporadic gunfire overnight kept tensions high.

Hoda al-Turk, a spokeswoman for the UN Relief and Works Agency for Palestinian Refugees, told The Associated Press that more than 5,000 families -- or about 25,000 refugees -- have left the camp since the fighting began last weekend.

About 31,000 people live in the camp.

However, despite the lull in fighting and the fact many had safely fled, there were signs that the standoff was still a long way from a resolution.

On Sunday, in a video obtained by AP Television News, the head of the militant group occupying the camp vowed his fighters would never surrender.

"We wish to die for the sake of God ... Sunni people are the spearhead against the Zionist Americans," said Shaker Youssef al-Absi, who is suspected of having ties to al Qaeda.

In the video, 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.

Meanwhile, the Lebanese military has been amassing troops, tanks and artillery around the camp and appears to be preparing for a major clash.

The government has vowed to crush the militant group, which claims it has more than 500 well-armed troops inside the camp.

Fighting broke out in Tripoli last Sunday, when Lebanese security officials raided an apartment where members of Fatah Islam -- a militant Islamist group lined to al Qaeda -- were holed up, sparking a gun battle.

The militants eventually made their way to the Nahr al-Bared Palestinian refugee camp where they took over military checkpoints outside the camp as well as positions within.

At least 20 civilians and 30 troops have been killed in the fighting this week. According to the Lebanese military, 60 militant fighters have been killed.

However, Fatah Islam has claimed only 10 have been killed.

The nation's ties are deeply divided between those who support the pro-Western government and those who back the Hezbollah opposition -- which has the support of Iran and Syria, the U.S.'s two main foes in the Mideast.

As a result, U.S. military aid that arrived on Saturday is likely to be a sensitive issue, coming amid opposition accusations that the government is already too closely allied with the U.S.

Sheik Hassan Nasrallah, the leader of Hezbollah, has called for a negotiated solution to the standoff, instead of a military one.

Defence Minister Elias Murr said he is leaving room for political negotiations, but said the military will do whatever is necessary, if talks fail.

Palestinian factions have been scrambling to find a negotiated solution to end the siege and avert what many fear would be a bloody battle between the Lebanese army and the Fatah Islam militant group in Nahr al-Bared.

With files from The Associated Press