A new video has been released showing another Briton believed to be held hostage by Islamic State militants.
In the footage, the man who identifies himself as journalist John Cantlie, is sitting behind a desk as he speaks to the camera.
The hostage, dressed in orange, said he wanted "to convey some facts" which "if you contemplate might help preserving lives".
Mr Cantlie said that over a series of programmes he will "show you the truth" as the western media "tries to drag the public back... to another war" with IS.
It is not apparent whether or not he was under pressure to deliver the message.
Islamic State has taken over large parts of Syria and Iraq
The insurgent group, which controls large parts of Syria and Iraq, has previously killed three western hostages - Briton David Haines and Americans James Foley and Steven Sotloff.
And it has threatened the life of UK aid convoy volunteer Alan Henning.
The latest footage is filmed against a dark background, unlike the videos of the beheadings, which have shown hostages against desert backgrounds.
Sky's Foreign Affairs Correspondent Lisa Holland said the new video shows the captive "is alive and seemingly well. He sits behind a desk with a message".
"He has a black background which is presumably a device being used by IS because they do not want to give clues as to his current whereabouts".
The captive said: "I know what you're thinking. 'He's only doing this because he's a prisoner."
At this point he raises his right hand and puts two fingers to his head, imitating a gun.
He said: "He's got a gun at his head and he's being forced to do this - right?'
"Well, it's true. I am a prisoner, that I cannot deny. But seeing as I've been abandoned by my government and my fate now lies in the hands of the Islamic State, I have nothing to lose.
"Maybe I will live, maybe I will die. But I want to take this opportunity to convey some facts that you can verify. Facts that if you contemplate might help preserving lives.
"Over the next few programmes I am going to show you the truth as the western media tries to drag the public back to the abyss of another war with the Islamic State.
"After two disastrous and hugely unpopular wars in Afghanistan and Iraq, why is it our governments appear so keen to get involved in yet another unwinnable conflict?"
"I'm going to show you the truth behind the systems and motivation of the Islamic State and how the western media...can twist and manipulate that truth for the public back home. There are two sides to every story. Think you're getting the whole picture. "
He ended by saying: "Join me for the next few programmes and I think you maybe surprised by what you learn."
The photographer said he had worked for the Sunday Times, Sun and Sunday Telegraph, said he had been captured by IS in Syria in 2012.
He was previously taken hostage in July 2012, but was liberated by the Free Syrian Army only to be recaptured after returning to Syria.
Security expert Baroness Pauline Neville-Jones told Sky News: "It does sound like they (the IS militants) are finding another tactical means of putting across a message designed to divide, instil fear and keep their profile up, while not engaging in another execution."
this is getting ... interesting
