A group of Syrian rebel fighters late Friday seized control of a crossing on the Iraqi border, the Syrian Observatory for Human Rights said.

The militants entered Syria from Jordan, where they had been trained, and swept into the border point at Al-Tanaf, which is controlled on the Iraqi side by the Islamic State group.

IS had seized control of Al-Tanaf from Syrian government forces in May 2015, depriving the regime of its last crossing with Iraq. 

But a barrage of air strikes by a US-led coalition had forced them to withdraw from Al-Tanaf, Observatory head Rami Abdel Rahman said.

In June 2014, IS declared a self-styled caliphate across parts of Syria and Iraq where it implements its ultra-conservative interpretation of Islamic law. 

Along the rest of the border with Iraq, IS controls the key Albu Kamal crossing but Kurdish fighters control Yarabiyah, further north.

In the summer of 2015, IS lost control of the strategic Tal Abyad border point, along the Syrian-Turkish border, to Kurdish forces. 

More than 270,000 people have been killed since Syria's conflict erupted in March 2011 and millions have been forced to flee.

A partial truce has seen violence drastically reduced over the past week, but the deal does not include zones controlled by IS or its jihadist rival, Al-Qaeda's local affiliate the Al-Nusra Front.