Beirut: Syria’s Al Qaida affiliate lost ground to its jihadist rivals around a town on the Iraqi border on Thursday in heavy fighting that left 24 people dead, a monitoring group said.

Fighters of the Islamic State of Iraq and the Levant (Isil), a cross-border group that has been disowned by the Al Qaida leadership, launched a three-pronged assault on positions held by Al Qaida affiliate Al Nusra Front and its allies, the Syrian Observatory for Human Rights said.

Isil fighters were driven out of Albu Kamal in heavy fighting earlier this year and are seeking to link up with their comrades over the border in Iraq, Observatory Chief Rami Abdul Rahman told AFP.

“Since dawn there has been fierce fighting inside Albu Kamal. Isil is advancing and has taken control of several neighbourhoods of the town which were previously held by Al Nusra Front and Islamist brigades,” he said.

A rebel commander loyal to the mainstream Free Syrian Army said it continued to control the nearby border crossing to the Iraqi town of Al Qaim and an AFP correspondent on the Iraqi side saw the FSA flag still flying over it.

“We are still controlling the border crossing,” the rebel commander told AFP on condition of anonymity. “Isil are attacking our positions in Albu Kamal, and the battles since yesterday (Wednesday) are in three different areas about 15 kilometres from the centre of the city. The battles are still continuing.”

Albu Kamal has been under the control of fighters opposed to the Damascus regime since November 2012 but Al Nusra and its allies forced out Isil fighters in heavy fighting earlier this year.

The Euphrates valley town had a pre-war population of some 70,000. Syrian government troops control just one official crossing on the Iraqi border — Al Tanaf/Al Walid on the main highway to Baghdad. A third crossing, Yarabiyah/Rabia in the north east, is controlled by Kurdish militia.