An air strike has killed 28 civilians in one of the last holdouts of the Islamic State group in Syria's eastern province of Deir Ezzor, a monitor said on Friday.

 

The raid late Thursday hit a "gathering of civilians" at an ice factory near the village of Al-Soussa near the Iraqi border, the Britain-based Syrian Observatory for Human Rights monitor said.

 

It was not immediately clear if the strike was carried out by an Iraqi plane or by one of the US-led coalition fighting IS, the monitor said.

 

Iraqi warplanes have recently carried out strikes in eastern Syria, while coalition aircraft have been supporting Kurdish-led fighters battling the jihadists.

 

State news agency SANA reported the strike late Thursday, saying more than 30 civilians were killed and accusing the US-led coalition.

 

The coalition was not immediately available for comment.

 

IS fighters swept across Syria and Iraq in 2014, declaring a cross-border "caliphate" in areas they controlled.

 

They have since lost most of that territory to various offensives, but still retain pockets in Syria including in Deir Ezzor.

 

Al-Soussa lies to the east of the Euphrates River, which runs diagonally through Deir Ezzor, splitting the province in half.

 

Russia-backed regime forces have pushed back the jihadists on the western side of the Euphrates, while the US-backed Syrian Democratic Forces alliance have battled them to its east.