Fresh clashes erupted in the Palestinian Yarmuk camp in southern Damascus during the night, a watchdog said on Wednesday, a week after major fighting there sent some 100,000 refugees fleeing for safety.
The latest violence came despite an agreement between rebels and pro-regime Palestinian fighters that they would withdraw from the camp, which houses some 150,000 people.
"The camp was relatively quiet until Tuesday night, but new clashes broke out that lasted through the early hours of the morning," said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.
Violence first broke out in Yarmuk when regime warplanes carried out an air strike on the camp on December 16, killing at least eight people.
Fighter jets carried out a second raid two days later, according to the Observatory.
For five days, battles in the camp pitted Syrian and Palestinian rebels opposed to the regime of President Bashar al-Assad against pro-Damascus Palestinian militia.
The army surrounded the camp but allowed people who initially fled to return last Thursday.
Abdel Rahman said a reported agreement between rebels and pro-regime militia to withdraw all fighters "has not succeeded".
"Clashes near the camp have not stopped in recent days, nor have snipers withdrawn or stopped shooting and killing people in Yarmuk."
Abdel Rahman also said he was "fearful of a plot to keep Yarmuk within the Syrian conflict" despite many Palestinians' wish to remain neutral in the fighting.
"A large number of people will be displaced, and many people might be killed," if fierce new battles occur in the densely populated camp, he said.
In recent months, Yarmuk has also become home to hundreds of Syrian families displaced by violence in their districts.
More than 700 Palestinians have been killed in Syria since the conflict erupted more than 21 months ago, a Palestine Liberation Organisation official in charge of refugees said on Sunday.