BEIRUT: At least 47 fighters were killed in clashes between the Islamic State group and rival Syrian rebels, a monitor said on Saturday, in an area where the United States and Turkey are planning to open a new front against Islamic State militants. The renewed fighting raged on Friday around the rebel-held town of Marea, 20 km (12 miles) from the Turkish border, the Britain-based Syrian Observatory for Human Rights said. The area falls within a 'safe zone' Turkey said last month it would set up in northern Syria to help keep Islamic State at bay. Islamic State said late Friday it had waged a fresh assault on Marea, killing 'dozens' of Syrian rebels fighting against it.