The Prime Minister has called the apparent beheading of US journalist Steven Sotloff by Islamic State militants "an absolutely disgusting and despicable act."
BREAKING. Cameron on Sotloff 'it's an absolutely disgusting and despicable act'
Mr Cameron said that he will make a statement later.
I've been told at the Nato summit that the intelligence services know exactly who 'Jihadi John' is - or at least are 99.9% certain.
The British aid worker being held by Islamic State is David Haines, a 44-year-old father-of-two from Perth, Scotland.
In a video statement which claims to record his final words US hostage and journalist Steven Sotloff blames US foreign policy for his death.