Kurdish forces yesterday accused Turkish-backed fighters of violating the ceasefire in northeast Syria with a “vast” new ground offensive and pleaded with the US “to intervene immediately” to stop the assault.

Less than 24 hours after Donald Trump boasted of establishing a "permanent" peaceful settlement in the area, the Syrian Democratic Forces (SDF) said they were under assault from Turkish-backed Syrian rebels.

“The SDF…holds the Turkish side responsible for the deterioration of the ceasefire process and calls on the American guarantor to intervene immediately to stop this aggression against our people,” a spokesman said.

Turkey said five of its soldiers were injured when Kurdish forces attacked near the border town of Ras al-Ain with mortars and drones. A car bomb also exploded in the Turkish-controlled town of Tal Abyad, wounding several people.

The renewed fighting undercut Mr Trump’s claim of "a major breakthrough" in northeast Syria and raised questions about his decision to retract sanctions on Turkey because it had halted its offensive.