*GRAPHIC* ..... Merciless Islamic State of Iraq and Syria terrorists savagely executed hundreds of captured Syrian soldiers, new video shows.

Fighters from the Islamic State in Iraq and Syria have killed more than 100 Syrian soldiers they captured after seizing an airbase in the northeastern part of the country, according to activists who track casualties in the Syrian conflict and an ISIS fighter who was reached through the Internet.

The mass killing marked a dark end to the battle for control of the Tabqa air base in Raqqa Province. The insurgents seized the base on Sunday after the deadliest fighting so far between ISIS and the government forces.

Video images posted on Thursday showed a group of men, stripped down to their underwear, being marched through the desert to a patch of sand, where they were gunned down, the ISIS fighter said. Whether the men shown in the video were the captured Syrian soldiers or other victims of the group could not be immediately confirmed.

More footage of the marching of soldiers and aftermath is contained in the video uploaded earlier: http://www.liveleak.com/view?i=163_1409228428