The US-led coalition fighting the ISIS group called on Thursday for an end to clashes in northeast Syria, where the Kurdish-led force it backs has been locked in deadly fighting with Arab tribes.
"The violence in northeast Syria must cease," the coalition said in a statement, saying that "distractions" from fighting ISIS sleeper cells risked a resurgence of the group.
Clashes broke out on Sunday after the Kurdish-led Syrian Democratic Forces arrested Ahmad Al Khubail, alias Abu Khawla, who headed its Deir Ezzor Council.
At least 40 fighters from both sides and another 15 civilians have been killed in the violence, according to local sources and witnesses.
The US-led coalition helped the SDF - which includes a smaller Arab component - oust ISIS from swathes of territory in northern and eastern Syria over the last seven years.
ISIS lost its last territorial bastion of Baghouz, which lies in Deir Ezzor, in 2019 to the SDF. IS still operates sleeper cells across parts of Syria and have waged hit-and-run attacks.