U.K. Intelligence Investigating as the Next 'Jihadi John' Emerges

Updated | British Prime Minister David Cameron on Monday condemned a video released by the Islamic State militant group (ISIS), which appears to show an English-speaking masked man and young English-speaking boy threatening the U.K., as "desperate stuff."

The U.K.'s intelligence and security services are examining the ISIS video that shows the killings of five men who the militant group accused of spying for the U.K.

The masked militant and the young boy, estimated to be no older than seven-years-old, appear to speak with British accents. In the 10-minute video, the masked militant threatens attacks in the U.K, calling Cameron an "imbecile" and "slave of the White House," and the boy, clad in the group's military attire, talks about killing "unbelievers" after the executions are shown.

The British leader, on a visit to east London on Monday, said the video was an act of desperation from an "appalling organization" that is on the back foot in Syria and Iraq.

"It's desperate stuff from an organization that really does do the most utterly despicable and ghastly acts and people can see that again today," he said. "But this is an organization that's losing territory, it's losing ground, it's, I think, increasingly losing anybody's sympathy."

Authorities investigating the footage plan to carry out voice-print analysis to match the pair's voices against that of individuals known to have travelled to Syria and Iraq. Security services believe that, of 800 British nationals who have travelled to fight with radical Islamist groups since 2011, 300 remain in either country. ISIS has frequently used children, which the group refers to as its "cubs of the caliphate," in its propaganda videos, purporting to show them executing alleged spies in Iraq and Syria.

The masked man, who is filmed holding a gun, says Cameron shouldn't have dared to "challenge the might" of ISIS, the Guardian reports. The U.K. began flying airstrikes against the group in Syria in December 2015. After delivering his message, the jihadist shoots the five men, who are dressed in orange jumpsuits, in the back of the head.

"One would have thought you would have learnt the lessons from your pathetic master in Washington and his failed campaign against Islamic State," the masked militant said in the video.

He added: "But it seems that you, like your predecessors Blair and Brown, are just as arrogant and foolish. In fact David you are more of an imbecile. You will lose this war as you lost in Iraq and Afghanistan."

Before the executions, each of the five men make an apparent "confession" of their crimes. One says he provided intelligence about the location of ISIS militants to help better target British airstrikes. None of the group claim to be from the U.K., some say they come from the Syrian capital of Raqqa, while one says he's from the Libyan city of Benghazi.

A spokesman for the U.K. foreign office said that the government is "aware of the video and [is] examining its content."

This is the second time that ISIS has used a British sounding executioner in its videos. Mohammed Emwazi, the British man that the media nicknamed "Jihadi John," carried out the beheadings of the two U.S. journalists James Foley and Steven Sotloff, as well as the two British aid workers David Haines and Alan Hennings. Emwazi was killed in a U.K.-led drone strike in Syria in November.

January's video comes after a military setback for ISIS—the group recently lost control over most of the Iraqi city of Ramadi, which was part of its so-called "caliphate" or Islamic State. Security analysts say the video could be a deflection from this defeat.

This story has been updated to include comments made by Prime Minister David Cameron, to the BBC today, while on a tour of east London.