DAMASCUS - Syrian rebels made advances on Tuesday in fierce fighting for a Palestinian refugee camp in south Damascus that sent tens of thousands of residents fleeing as the army prepared a counter-attack and carried out fresh air raids.

The United Nations Relief and Works Agency said at least half of Yarmuk’s population of more than 112,000 had fled the violence rocking the 2.1 square-kilometre (about one square mile) camp.

An AFP correspondent at the border reported an influx of hundreds of Palestinians into neighbouring Lebanon in the face of the fierce fighting between Syrian rebels and their Palestinian allies, and Palestinian factions still loyal to Damascus. President Bashar al-Assad’s forces carried out several air raids on the Yarmuk district, on the southern outskirts of Damascus, as people were fleeing the area, the Syrian Observatory for Human Rights said. Earlier air strikes targeted the eastern outskirts of the capital as well as the southern district, killing three civilians, and clashes also erupted near the airport road, the Britain-based watchdog said. Nationwide it said 61 people died in violence.

Fighting had rocked the Yarmuk camp during the night as the insurgents backed by some Palestinian fighters launched an offensive to push out a pro-regime Palestinian faction.

An AFP journalist at the scene said army checkpoints were set up at the northern and southern entrances. Soldiers were preventing anyone from entering the camp, while dozens of families could be seen with suitcases in hand waiting to leave aboard pickup trucks. The population of the camp had halved by Tuesday, according to UNRWA. Many have fled to neighbouring Lebanon. A large number of buses and cars filled with Palestinians were waiting to enter Lebanon through the Masnaa border crossing on Tuesday, an AFP photographer said.

Syrian Observatory director Rami Abdel Rahman said: “There are definitely Palestinians fighting with the rebels.” Ekmeleddin Ihsanoglu, head of the Organisation of Islamic Organisation, said “neither the regime nor the opposition can be excused” for the clashes at the camp. The World Food Programme warned that the spiralling violence across Syria was making it increasingly difficult to distribute food to trapped civilians.

Meanhwile, Turkey urged Iran to pressure Syria’s regime to stop violence against its own people, as Turkish premier Recep Tayyip Erdogan brushed off Iranian criticism of Ankara’s plans to deploy Patriot missiles as “random remarks”.

Turkish Foreign Minister Ahmet Davutoglu waded into the diplomatic melee Tuesday, urging Tehran to focus its energies on sending “clear messages” to the Syrian regime rather than protesting the missile deployment. “Instead of criticising the (Patriot missile) system, Iran should say stop to the Syrian regime that has been continuously oppressing its own people and provoking Turkey through border violations,” Davutoglu told reporters in Ankara.

One of the highest-profile US journalists to report from Syria, Richard Engel of NBC, was meanwhile freed after a firefight between his pro-regime militia captors and rebels fighters. NBC said Engel, 39, and his TV crew went missing shortly after crossing into Syria from Turkey on Thursday, and that it had not been able to contact them until it learned they had been freed on Monday.