Islamic State killings: Siddhartha Dhar 'is main suspect in IS video'

The main suspect in the latest propaganda video by so-called Islamic State is thought to be British man Siddhartha Dhar, the BBC understands.

An official source told the BBC Mr Dhar was the focus of investigations into the video, which purports to show the killing of five men.

A woman has also told the BBC's The One Show that she believes the young boy featured in the video is her grandson.

Security correspondent Gordon Corera reports.