BEIRUT: Rebel groups including the jihadist Al-Nusra Front have set up a religious council to administer affairs in the east of Syria which is mostly under their control, activists said on Sunday.

"God commanded the Islamic battalions to form a religious council in the east to administer the affairs of the people and fill a security gap," the groups said in a statement distributed by the Syrian Observatory for Human Rights.

The council will include several offices charged with functions including justice, policing and emergency services, the statement said.

Video footage distributed by the Britain-based Observatory showed an Islamist convoy draped with black flags bearing Islamic inscriptions and driving in the Deir Ezzor area of the east.

The video shows rebels attaching a banner to a building in the town of Mayadeen, on which is written "Religious Committee of the Eastern Region."

Rebels in the eastern provinces of Deir Ezzor, Hassaka and Raqa have made significant military gains as they battle forces loyal to President Bashar al-Assad in the country's oil-producing region.

The Al-Nusra Front, completely unknown before the rebellion in Syria that began two years ago, has been a rebel standard-bearer since mid-2012 when it became the spearhead of the insurgency ahead of the Free Syrian Army.

FSA fighters, composed mainly of army deserters, have told AFP that despite being fewer in number, the Al-Nusra jihadists have better logistic and economic backing and receive financing "from abroad."

The Front has gone for strategic targets in the east such as oil wells, and also recruits local fighters and pays them.

Al-Nusra makes no secret of its aims to see Syria become an Islamist state. Damascus accuses both Saudi Arabia and Qatar of financing Islamist groups battling the Assad regime.