“The Islamic State now controls 90 per cent of the camp,” said Rami Abdel Rahman, head of the Britain-based Syrian Observatory for Human Rights.
The United Nations warned of a “dire” humanitarian situation for about 18,000 Palestinians, including 3,500 children, trapped inside the camp. Yarmouk, under government siege since 2013, is strategically located on the southern tip of Damascus.
“The situation that the inhabitants of Yarmouk currently face is one of the most severe ever,” Pierre Krahenbuhl, head of the UN Relief and Works Agency for Palestine Refugees, told the UN Security Council in New York.
Aknaf Beit al-Maqdis, a Palestinian faction opposed to the Syrian government and seen as being allied with the Islamic Hamas movement, has been battling the Islamic State fighters in the camp but is being pushed back.
The faction is “now confined to the north-eastern section of the camp only,” according to Abdel Rahman, whose group gathers information on the Syrian conflict through a network of pro-opposition activists throughout the county.
A video posted online showed Islamic State fighters, some draped in the group’s flag, combing deserted areas inside the camp and chanting, “God is great.”
Reports on social media accounts and from Palestinian officials claimed the Islamic State beheaded several people and was making arrests.
Syrian government forces have also launched airstrikes and surface-to-surface missiles against Islamic State positions. Shelling continued into the afternoon.
“The shelling has not stopped since the early hours of the morning, especially in areas where Aknaf Beit al-Madqis have posts,” Abu Mohammed, a Palestinian who is still inside the camp, said by telephone.
An official in the Palestine Liberation Organization (PLO) in Beirut said Islamic State has been preparing to take over the camp for months using “sleeper cells.”
Ousama Hamdan, a Hamas spokesman in Beirut, described what is going on inside the camp as “serious and suspicious.”
Hamdan, Aknaf Beit al-Maqdis and the PLO official accused militants with the al-Nusra Front, al-Qaeda’s wing in Syria, of facilitating the entry of Islamic State fighters into the camp. Syrian rebel groups made similar allegations.
Al-Nusra has formally claimed it is neutral, but other groups fighting in the camp said it is preventing rebels from entering it to help the Palestinians and rebel factions fend off Islamic State aggression.
“Our fighters are not engaged in such battles [in Yarmouk],” said Abu al-Fadel, a spokesman for al-Nusra. “Our main aim is to fight the regime traitors.”
Most Palestinian factions have issued calls for an end to the fighting and for the delivery of humanitarian aid.
The camp has largely been under siege by government forces since 2013 after rebel factions gained a foothold in the area. Some restrictions on the camp have been eased in the past year although the UN says it had only limited access to the camp to deliver aid.
Northern parts of the camp have suffered heavy damage, and many buildings, including medical centres, have been destroyed. The UN said the camp currently has no safe water supply.
Krahenbuhl called on UN Security Council members to act in unity and exert pressure on parties on the ground.
The council expressed “deep concern” over the escalation of the violence and urged the lifting of sieges and the protection of civilians, said Dina Kawar, Jordan’s UN ambassador and current president of the council.
“The members are looking to further measures that can be taken to help in providing the necessary protection and assistance,” Kawar said.
Prior to the outbreak of the Syrian civil war in 2011, the camp housed about 150,000 Palestinians who fled the Arab-Israeli war in 1948.
Some Palestinian factions have gotten caught up in the civil war, either supporting the government or the opposition, while others have attempted to stay neutral and keep the camps out of the bloodshed.
According to the UN, 560,000 Palestinian refugees lived in Syria before the war. Currently, about 460,000 refugees remain in the country with half of them displaced internally by the conflict.