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.