ISIS attacked Syrian government-held areas in the eastern city of Deir al-Zor and an air base south of the city.

Islamic State of Iraq and Syria (ISIS) militants attacked Syrian government-held areas in the eastern city of Deir al-Zor and an air base south of the city on Friday, a monitoring group said, and fighting killed at least five civilians.

The fresh assault looked aimed at taking over the few remaining areas controlled by the government in Deir al-Zor province, which is mostly under ISIS control, the Syrian Observatory for Human Rights said.

Government forces bombarded other areas of the city and around the air base during fighting that came a day after pro-Damascus media reported Russian jets had struck the province.

Five civilians — a mother and four of her children — were killed in government shelling in the city, the Observatory said.

ISIS militants, meanwhile, appeared to be advancing, taking over the post office building in Deir al-Zor after detonating a car bomb in the city, and moving in on the air base, the Observatory said.