DAMASCUS, Sept. 25 (Xinhua) -- Russian airstrikes and artillery fire hit positions of the U.S.-backed Syrian Democratic Forces (SDF) in Syria's eastern province of Deir al-Zour on Monday, the SDF said in a statement.
The SDF positions were hit near the Conoco natural gas field and the Azbeh station as well as the textile factory northeast of Deir al-Zour, said the statement.
The Conoco gas field is the first energy plant to fall in the hands of the SDF two days ago, since they unleashed an offensive against the Islamic State (IS) group in that oil-rich province earlier this month.
The SDF said it had lost several fighters in the Russian shelling.
Meanwhile, the group condemned the attack as "treacherous," saying its attack against IS in Deir al-Zour was coordinated with the U.S.-led coalition.
It added that the SDF fighters have avoided being dragged into a sideline skirmish, to save the resources to fight IS.
"We strongly condemn the aggressive attacks of the Russian forces and their allies on ground, which only serve terrorism and harm the war on terror," the statement said.
It stressed that "we will not stand indifferent about such attacks and we will use our right of self-defense."
The statement urged the Russian forces to "halt their aggressive stance toward our people and forces."
The SDF is an alliance of Kurdish, Arab and Assyrian fighters led by the Kurdish YPG group and heavily supported by the United States.
The group has been fighting IS in northern Syria since it was formed in 2015.
The group has taken over 90 percent of the Raqqa province, the de facto capital of IS in northern Syria.
