An RAF drone strike has stopped a public execution by Isis in Syria, the Ministry of Defence has said.

The Reaper drone initially spotted a group of fighters from the terror group, also known as Daesh, mustering a large crowd in the town of Abu Kamal in eastern Syria.

A Ministry of Defence spokesman said: “When a van then unloaded two shackled prisoners in front of the crowd, it became clear that Daesh were organising a public execution.

“Given the large number of civilians present, the Reaper's crew could not target directly the Daesh fighters about to carry out the murders.

“However, two armed extremists were stationed as sentries on the roof of a building overlooking the scene.

“A Hellfire missile was fired immediately, and scored a direct hit which not only killed one of the sentries but also brought the execution to an immediate halt, as the Daesh fighters fled the scene, and the crowd of civilians dispersed.”

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The attack took place on Tuesday last week.

Between December 2015 and December 2016 the RAF launched 73 air strikes over Syria, killing an estimated 120 Islamic State fighters and injuring a further 12.