Video shows captured Syrian soldiers executed by Islamic State
Video posted on You Tube shows dozens of bodies after slaughter following fall of airbase
The video, confirmed as genuine by an Islamic State fighter, showed the bodies of dozens of men lying face down wearing nothing but their underwear. They were stretched out in a line that appeared to be dozens of metres long. A separate pile of bodies was shown nearby. The authenticity of the video could not be independently verified.
The caption beneath it said the dead numbered 250. The Syrian Observatory for Human Rights, which monitors violence in the war, put the death toll at more than 120.
Islamic State stormed Tabqa airbase on Sunday after days of clashes with the army and said it had captured and killed soldiers and officers in one of the bloodiest confrontations yet between the two sides.
The capture of Tabqa, the Syrian army's last foothold in the area, and apparent killing of large numbers of its soldiers shows how Islamic State has cemented its grip on Syria's north.
The video begins by showing the captives apparently being marched in the desert with their hands behind their heads. An Islamic State fighter repeatedly shouts out "Islamic State", to which the men reply "It shall remain".