The Islamic State-affiliated Amaq agency uploaded video on Tuesday claiming to show ISIS fighters taking over parts of the Yarmouk Palestinian camp which has mostly been under the control of al Nusra Front for a year.
A voice over the pictures said they had taken control of the al-Orouba 'barrier'. Al Nusra Front headquarters were said to be in the Al-Orouba area, adjacent to the stadium in the camp, a document released by the Action Group for Palestinians of Syria said last year.
The voice also said they had taken control from 'the Joulani Front' referring to al-Nusra Front's leader Abu Mohammed al-Joulani.
An ISIS fighter held up an Al Nusra Front flag at the end of the video, near a mosque.
Al Qaida-linked Al Nusra pushed out most IS fighters from Yarmouk in April 2015 and was the main group in control though others were also inside the camp.
The camp, on the outskirts of the Syrian capital Damascus, was set up in 1957 to house Palestinians. The camp was home to some 160,000 Palestinians before the Syrian conflict began in 2011, refugees from the 1948 war of Israel's founding, and their descendants.
Nusra was accused by its rivals last year of facilitating the entry of Islamic State militants into the camp. Although they are rivals elsewhere in Syria, both share a loathing for Aknaf al Maqdis who had taken control parts of the camp.