A video has surfaced showing the moment a Royal Air Force (RAF) drone fires a missile and stops a public execution by Isis in Syria.

Footage released by the UK Ministry of Defence (MoD) shows a crowd being forced at gunpoint to gather in a square in the town Abu Kamal to watch the execution of two prisoners.

However, when pilots at RAF Waddington in Lincolnshire – about 2,000 miles away – fired a Hellfire missile, the crowd scatters in panic, prompting the militants to put a halt to the execution. The missile targeted a sniper tasked with shooting at the two prisoners.

The remote-controlled Reaper drone fired the missile in May, but footage of the event has only been released now. The mission was overseen from the operations centre (Caoc) at the Al Udeid air base in Qatar.

"The individual whom we engaged was a sniper in over-watch to shoot civilians who sought to move away from the execution, let alone to protect the planned execution itself," Air Commodore Johnny Stringer, commander of UK air operations in Iraq and Syria, told Mail Online.

"That particular example for us very much brought it home because civilians had been herded in, forced literally at gunpoint, to go and watch this going on in their hundreds."

At the time the event took place the MoD explained that the drone had been flying over Abu Kamal when it noticed the crowd gathering in the square.

"When a van then unloaded two shackled prisoners in front of the crowd, it became clear that Daesh [Isis] were organising a public execution," MoD said.

"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,"the MoD continued.

Drone disrupts Isis execution in Syria
Footage released by the Ministry of Defence (MoD) shows the moment a remote-controlled drone fires a missile disrupting a planned execution by Isis terroristsMinistry of Defence

When Isis emerged in 2014, it seized large territories across the Middle Eeast, making Mosul in Iraq and Raqqa in Syria the respective capitals of its self-declared Caliphate. The group has now lost most of the territories due to regional offensives led by international coalitions.

British military officials told Sky News they have been able to identify and neutralise several senior Isis commanders, including "those who are enabling directly attacks in Europe, including the UK".

However, they added, the Isis cells keeps moving and it is still able to mastermind attacks, including in the West.

"It [the cell] is likely moved – we don't know for sure that it was ever in one specific location," a British military intelligence officer was quoted as saying.

"They're very, we call it 'operationally security aware' – so they know that if they're holed up in one building, doing one particular job from that building, then we'll soon find out," he continued.

"Key commanders will spread themselves around a place. We saw the movement out of Raqqa from these types of people much before the Raqqa operation really started in earnest."

Reaper Drone RAF Isis
How the MQ-9 Reaper works.Reuters