“Jabhat al-Nusra and ISIL were able to take control on 90% of the Yarmouk camp after violent clashes against Aktaf Bait al-Maqdis and Islamic battalions,” the Syrian Observatory for Human Rights said in a statement.
On Wednesday, ISIL entered Yarmouk, one of the biggest refugee camps in Syria, provoking clashes with other radical jihadist groups.
UN Relief and Works Agency (UNRWA) raised serious concerns over the situation in Yarmouk, as the clashes could cause damage to civilians, residing in the area.
Yarmouk used to be home to over 160,000 Palestinian refugees before a civil war between government forces and various militias, including Islamic State, broke out in Syria in 2011.
The camp has been struggling with a humanitarian crisis, being under siege by Islamist militants since late 2012.
Currently Yarmouk is the place of residence of 18,000 people, including some 3,500 children, according to the United Nations.