A video circulating online purports to show ISIS executing five men accused of spying for Britain in Syria.

The footage Sunday bears the markings of the ISIS media wing, and shows five men "confessing" to filming and photographing sites in exchange for money within Raqqa, the capital of the group's self-declared caliphate. It could not be independently verified.

The men, speaking Arabic, are introduced as "the enemy" and "apostates." Later they kneel lined up in orange jumpsuits in the desert, where they are shot in the head by masked executioners.

Before the shooting, a masked man with a British accent mocks British Prime Minister David Cameron, calls the men "spies," and says ISIS will one day invade Britain and impose their version of Islamic law.