A Kurdish female politician who had worked extensively to bring together Christians, Arabs and Kurds in Syria, has been executed by a Turkish-backed group.

Hevrin Khalaf, 35, was among nine people who were executed in the north-east of Syria, according to an alarming report from a human rights monitoring group.

Local media have reported that Khalaf was "taken out of her car during a Turkish-backed attack and executed by Turkish-backed mercenary factions".

The political arm of the Kurdish-led Syrian Democratic Forces has said, "This is a clear evidence that the Turkish state is continuing its criminal policy towards unarmed civilians."

The Kurdish politician had been returning back from a meeting in Kasakah when the vehicle she was travelling in was attacked.

Nine other civilians were also executed on the roadside after being dragged from their cars by Turkish-backed militia, with some of the killings captured by observers on mobile phones and posted onto social media.

The U.S. State Department has said, "We have seen reports of the killing of [Hervin] Khalaf....as well as several captured SDF fighters, the latter having been apparently shot while in the hands of Turkish Supported Armed Syrian Opposition elements.

"We find these reports to be extremely troubling, reflecting the overall destabilization of northeast Syria since the commencement of hostilities on Tuesday."

This week, Turkey and its allied forced commenced a military offensive to drive back the Kurdish People's Protection Units from near its borders. The move has taken place following President Donald Trump's announcement that U.S. troops would withdraw from the region.

Evangelical groups have condemned Trump's decision to withdraw U.S. forces from the region, warning that it would leave religious and ethnic minorities vulnerable to attack.