A new video has been released showing a British man believed tobe held hostage by Islamic State (IS) militants.
The man says he is journalist John Cantlie and that he is a prisoner.
Dressed in orange, Mr Cantlie, who in 2012 escaped an earlier kidnapping in Syria, asks why he and others have been abandoned by the US and UK governments.
IS has recently killed three hostages and, in a video showing the death of UK aid worker David Haines, threatened to kill British man Alan Henning next.
No IS militants are seen in the video, which is entitled "Lend Me Your Ears" and is addressed to the Western public.
In it Mr Cantlie says other European governments have negotiated for the release of their hostages but says the US and UK have done things differently.
"After two disastrous and hugely unpopular wars in Afghanistan and Iraq, why is it that our governments appear so keen to get involved in yet another unwinnable conflict?" he says.
He also says this is the first of several of what he calls programmes in which he will explain the philosophy of IS.
BBC security correspondent Frank Gardner said Mr Cantlie was speaking to the camera under duress.
He said it was like a "kind of parody of a chat show" and "very much a propaganda video".
"It doesn't end with any overt threat. He's reading from a script, there's no knife or gun being held to his head," our correspondent said.
He added that previous IS videos were directed at US and UK leaders, but this was meant for the British public, particularly Muslims.
The message of the video is that IS has been "misrepresented by the Western media", and the hostage says he is going to be revealing the truth about IS in "the coming programmes", our correspondent added.
From comments on the tape, it is clear it was made this year, but not precisely when.
Deputy Prime Minister Nick Clegg described IS as a "murderous, medieval, terrorist outfit".
"We didn't need any reminding that what we're dealing with here in Isil is a movement of almost unprecedented barbarity and cynicism," said Mr Clegg, who has not yet seen the video.
Foreign Secretary Philip Hammond said he would "look very closely" at any material released on the internet.
He said videos such as these could be "very distressing" to the families of the individuals involved.