Turkish authorities have placed under arrest a British citizen on charges of links to a Kurdish militia Ankara deems to be a terror group, after detaining him in a raid at a holiday resort, state media said.

Turkey's military said on Friday it was close to taking the northern Syrian city of al-Bab from Islamic State, a victory that would deepen Turkish influence in an area where it has created a de facto buffer zone.

Kurdish militia fighters in northern Syria will remain a target for Turkish forces as long as they are positioned west of the Euphrates river, Turkey's presidential spokesman said on Wednesday.