BEIRUT (AFP) -- Kurdish fighters in Syria seized a crossing on the eastern border with Iraq from jihadist rebel forces during fierce clashes at dawn on Saturday, a monitoring group said.

The Kurds "took control of the Al-Yaarubia border crossing with Iraq at dawn after clashes with the Islamic State in Iraq and the Levant, the Al-Nusra Front and other rebels," said the Syrian Observatory for Human Rights.

The clashes left fighters dead on both sides, said the Observatory, a Britain-based organisation that relies on a network of sources on the ground for its reports.

On Friday morning the Kurdish fighters had entered the town of Al-Yaarubia, which they have been fighting the jihadists for control of for several days.

The Kurds and the jihadists have been fighting for months for control of northeastern Syria, an area rich in oil and wheat.

The Observatory said on Thursday that it would be difficult for the Kurdish forces to overrun the post because it was controlled by many jihadist groups.

Rebels ostensibly fighting to overthrow President Bashar al-Assad have increasingly turned their guns on each other in recent months, with jihadists clashing with the mainstream Free Syrian Army in the north, where the rebels control vast swathes of territory.

Kurdish fighters affiliated with Turkey's separatist Kurdistan Workers' Party have meanwhile struggled to carve out an autonomous region in northeastern Syria similar to one in northern Iraq.