A funeral was held on Monday for Kurdish politician Hevrin Khalaf, other civilians and a number of captured Kurdish fighters killed at the weekend by Turkey’s Syrian allied forces near the town of Tal Abyad. Khalaf, 35, 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 said. "This is clear evidence that the Turkish state is continuing its criminal policy towards unarmed civilians," it said. Khalaf was the secretary-general of the Future Syria Party. The funeral was held in the town of Derik, known as Al Malikiyah in Arabic. Pro-Ankara fighters under the umbrella of a group called the National Army are taking part in a Turkish offensive on Kurdish-held border towns in north-eastern Syria. The United States said it was looking into reports that a Kurdish politician and captured Kurdish fighters were killed in north-eastern Syria amid Turkey's offensive, a State Department spokesman told Reuters on Sunday. He said Washington found the reports disturbing. "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," a State Department spokesman said, referring to Turkey-backed rebels. "We find these reports to be extremely troubling, reflecting the overall destabilisation of northeast Syria since the commencement of hostilities on Tuesday," the spokesman said in an email. Khalaf had been returning from a meeting in Hasakah at the time of the attack in which her driver and an aide were also killed, said Hussein Omar, the Future Syria Party's coordinator in Europe. Party officials including Khalaf have had contacts with US officials since it was founded in 2018, he said. Asked about the accusation that Turkey-backed groups had killed Khalaf, the spokesman for the Turkey-backed National Army, which groups Syrian rebel factions, on Saturday said they had not made it as far as that area. "We condemn in the strongest of terms any mistreatment and extrajudicial execution of civilians or prisoners, and are looking further into these circumstances," the US State Department spokesman said.