At least 26 militants were killed as Turkish-backed Syrian forces launched an offensive in the Manbij region of northern Syria, days after capturing a Kurdish-held enclave.

Pro-Turkish fighters had already taken control of the Kurdish enclave of Tal Rifaat last week, following a lightning offensive by Islamist-led rebels that ousted Bashar al-Assad in Damascus.

“Pro-Turkish groups took control of large districts of the city of Manbij in the eastern countryside of Aleppo after heavy clashes with the Manbij Military Council,” the Syrian Observatory for Human Rights said.

The council is linked to the Syrian Democratic Forces, which are dominated by the Kurds and are backed by Washington. The SDF controls large areas of northeastern Syria.

Nine pro-Turkish fighters and at least 17 members of the Manbij Military Council were killed in the clashes, according to the Observatory, which has a large network of sources in Syria.