A commander of the Palestinian Fatah party in Lebanon says seven militants who were fighting the Lebanese army have now surrendered to his group.
Troops have poured into the area around Nahr al-Bared camp
Khaled Aref said the Fatah al-Islam members, not connected to the mainstream Fatah, had laid down arms and promised to stay out of fighting.
Clashes broke out at the Nahr al-Bared camp for Palestinian refugees in north Lebanon 16 days ago.
More than 100 people have died in the worst internal feuding in years.
"They surrendered on Monday and Tuesday to Fatah men in the Nahr al-Bared camp," Mr Aref - Fatah's number two in Lebanon - told reporters.
"We can confirm that men from Fatah al-Islam turned themselves in and handed over their weapons."
On Monday the UN launched an urgent appeal for almost $13m to help thousands of Palestinians who had fled the camp.
The UN agency for Palestinian refugees said more than 27,000 Palestinians had sought refuge in another camp nearby, where the UN says conditions are now unbearably overcrowded.
Palestinian refugees have also been leaving Ain al-Hilweh camp in southern city of Sidon, after the fighting spread there on Sunday, involving another armed group.
Both camps were reported relatively quiet on Tuesday, although residents expected the fighting would resume.
Intermittent gunfire and shell bursts were heard through the day at the Fatah al-Islam's base in Nahr al-Bared.
Meanwhile, police in the capital Beirut are investigating the latest in a series of bomb explosions, in which at least 10 people were injured on Monday night.
Speaking after an emergency cabinet meeting, Information Minister Ghazi Aridi said the bombings and camp clashes were connected, although he did not publish proof.