David Cameron believes the so-called Islamic State video is clearly "propaganda" from the extremist group and it should be treated as such.

But the Prime Minister's spokeswoman says "it serves as a reminder of the barbarity" of the organisation.

Either way the government is examining the content of the video released yesterday to try to identify both the masked man and the young boy who appear in it.

Number 10 believes IS are under pressure from airstrikes and from Iraqi forces who recently re-took the town of Ramadi.

Mr Cameron's spokeswoman said there have been 11 British airstrikes in Syria since authorisation was granted by Parliament late last year, including one on Christmas Day at an IS checkpoint south of Raqqa.