Cairo, Aug 28 (IANS/EFE): Militants of the Islamic State (IS) Sunni extremist organisation have executed dozens of Syrian soldiers captured after the rebels seized al-Tabaqa military airport from government forces earlier this week, the Syrian Observatory for Human Rights (SOHR) reported Thursday.

SOHR said the soldiers were executed Wednesday after they tried in vain to hide somewhere between the town of al-Tabaqa in the northern province of al-Raqqa, and the area of Athraya.

A Syrian army convoy dispatched from al-Salmiya town failed to rescue the troops, while another military column managed to help 60 other soldiers hiding in Athraya.

The London-based organisation also said that 27 members of the government forces and eight militants were killed in battles fought near Athraya.

Meanwhile, online forums used by the militants said the number of soldiers executed on Wednesday was 200.

The IS Sunday gained full control over al-Tabaqa military airport, the last bastion of the Syrian regime in al-Raqa.

SOHR said more than 170 government troops, including non-commissioned officers, were killed during the struggle over the airport.

The UN commission investigating atrocities in Syria Wednesday accused the IS of committing war crimes and crimes against humanity, including torture, murder and rape.