Civilians trapped in a Palestinian refugee camp in Syria's capital have fled to safer areas amid intense shelling and clashes between Palestinian armed factions and the Islamic State of Iraq and the Levant (ISIL) fighters who took over most of the camp, Syrian activists said.

ISIL fighters stormed the Yarmouk camp in southern Damascus on Wednesday, marking the group's deepest foray yet into the city.

Palestinian officials and Syrian activists said ISIL fighters were working with rivals from the al-Qaeda affiliate in Syria, the Nusra Front. The two groups have fought bloody battles against each other in other parts of Syria, but appear to be cooperating in the attack on Yarmouk.

There was an agreement made under the table between the Nusra Front and ISIL. Many people were shocked, activist Hatem al-Dimashqi told Al Jazeera.

"Nusra Front released a statement claiming they were neutral but in reality it is not true. Nusra has several checkpoints inside Yarmouk, ISIL came right through with no difficulties and this is the most important reason ISIL was able to raid Yarmouk and control it."

A Damascus-based Palestinian official, Khaled Abdul-Majid, said the fighters controlled about half of the Yarmouk camp. The neighbourhood, set up as a Palestinian refugee camp in 1957, is inhabited by both Palestinians and Syrians and located on the edge of the Syrian capital. 

Civilians trapped

Al Jazeera's Stefanie Dekker, reporting from Beirut, the capital of neighbouring Lebanon, said on Saturday that despite calls from the United Nations and activists, the Syrian government was unlikely to open a humanitarian corridor for the 18,000 civilians who are still in the camp.

"It is a complex situation. The government forces control the northern part [of the camp] towards Damascus. It is their priority to keep the capital safe," said Dekker. "The fact that ISIL fighters are less than 10km away is of a huge concern. If they allow a humanitarian corridor, who will be coming out?"

A Syrian opposition bloc, the Syrian National Coalition, called the development "extremely alarming" and called on the international community "to take concrete immediate steps" to protect the civilians of Yarmouk.

"Palestinian armed groups alongside the Free Syrian Army are fighting to prevent ISIS from establishing a foothold in Damascus," Salem al-Meslet, a spokesperson of the Coalition, said, referring to ISIL with an alternative abbreviation. He said, however, that the groups were under-equipped.

In addition to the ground clashes, Syrian forces were shelling the camp.

The London-based Syrian Observatory for Human Rights, which monitors the Syrian conflict through a network of activists, reported a Syrian government air strike on Yarmouk, but said there was no immediate word on casualties.

Dimashqi, an activist based in an area just south of Damascus in Yalda, said mosques were blaring calls for blood donations in the areas surrounding the camp, including Yalda, Babila and Beit Saham as hospitals received wounded civilians from Yarmouk.

The United Nations has said about 18,000 civilians are trapped in Yarmouk, including a large number of children. The camp has been under government siege for nearly two years and has witnessed several rounds of deadly fighting between government forces and rebels.

UN aid workers have been sending food parcels into the camp in an effort to alleviate the extreme suffering inside.

Source: Al Jazeera And AP