A car bomb in northeast Syria targeting a checkpoint manned by Turkish-backed forces, killed six people, mostly fighters, near the border town of Ras al-Ayn on Thursday, a war monitor said.
The blast in the village of Tal Halaf held by Turkish forces and their Syrian allied fighters also wounded 15 others, the Britain-based Syrian Observatory for Human Rights said.
Turkish forces and their Syrian proxies last year seized a 120-kilometer (75-mile) stretch of land inside the Syrian border from Kurdish forces, running from Ras al-Ayn to Tal Abyad.
Many bombings have since rocked the area, five in the past week alone.
An explosives-rigged motorbike in Ras al-Ayn on Tuesday killed two civilians and a fighter, the Observatory said, two days after another in a vegetable market in the town killed eight people, six of them civilians.
On Saturday, nine people killed in a car bomb rocked the vegetable marketplace in Ras al-Ayn.
Turkish-bakced Syrian forces have thwarted an attack by Kurdish YPG militia in northeastern Ras al-Ayn region, a military source told Zaman al-Wasl.
The third infiltration attempt in a week into Ras al-Ayn was fended off by National Army fighters as YPG sleeper cells tried to carry out new blast attacks.
The Turkish military and the Syrian National Army attacked Kurdish forces in northeastern Syria on October 9 with the aim of creating a roughly 30-kilometer (20-mile) deep buffer zone.
Ankara views the YPG as a terrorist group linked to Kurdish militants on its own soil and has mounted military operations in northern Syria to push it back from the border.