ISIS militants have released a video purporting to show the killing of five men they claim were spying for Britain, accompanied by a message taunting Prime Minister David Cameron for challenging the "might" of the extremist group, also known as Islamic State or IS.
The Foreign Office said it was studying the contents of the 10-minute film, in which a man speaking with a British accent threatens attacks in the UK. A boy, also apparently speaking English, appears in the video — which has not been independently verified — talking about killing "unbelievers".
The propaganda film appeared less than two months since Mohammed Emwazi, a British ISIS militant who appeared in videos depicting executions, was killed in a US drone strike in Syria.
The latest video appears to show another man trying to assume the former role of Emwazi, also known as Jihadi John. It will be studied intensively by British intelligence.