The Islamic State group launched an attack on Friday on Syrian Democratic Forces' positions in Hajin region in southeastern Syria, Mustafa Bali, the head of the SDF media office said.
"ISIS is launching a huge attack, heavy clashes are taking place there," he tweeted. "Only 35 percent percent from Hajin is liberated by our forces."
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Meanwhile, top Syrian Kurdish official Ilham Ahmed said Kurdish-led forces in northern Syria may not be able to continue hold Islamic State prisoners if the situation in the region gets out of control.
Speaking alongside her at a Paris news conference, Riad Darar, co-chair of the Syrian Democratic Council, said they hoped France would play a more active role in Syria after U.S. President Donald Trump decided to withdraw U.S. forces.
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"Under the threat of the Turkish state, and with the possibility of Daesh (Islamic State) reviving once again, I fear the situation will go out of control and we no longer be able to contain them," Ahmed said when asked if the SDF was considering releasing hundreds of IS detainees.
The two had earlier met advisers to French President Emmanuel Macron to discuss Trump's decision, which took U.S. allies by surprise. French officials declined to immediately comment.
France has about 200 special forces personnel operating in Syria's Kurdish areas as well as heavy artillery as part of efforts to rout Islamic State in its remaining pockets. It is also carrying out air strikes.
"We do not share the analyses that the territorial caliphate (of Islamic State) has been annihilated," French Defence Minister Florence Parly said on RTL radio, disagreeing with Trump's assessment.
"It's an extremely grave decision and we think ... the job must be finished."