A VIDEO purporting to show an Islamic State fighter speaking with a British accent beheading an American journalist is being investigated by the Obama administration.

A man claimed to be James Foley, who went missing in Syria in 2012, is seen kneeling in a desert-like environment at an unknown location as an IS fighter stands by his side dressed in black and with his face covered.

The victim, wearing an orange outfit, makes a statement during the five-minute video entitled "A message to America" released by the Islamic State Al-Furqan foundation.

During the speech he said he wanted to call on family, friends and loved ones to "rise up against my real killers, the US government".

He added: "For what will happen to me is only the result of their complacency and criminality".

The statement, during which he is seen to pause and take deep breaths, ended with him saying he wished he could see his family again.

The IS fighter standing next to him is then seen brandishing a knife before accusing America of "aggression towards the Islamic state".

He said: "You have plotted against us and gone far out of your way to find reasons to interfere in our affairs."

In a chilling threat in which he singles out President Barack Obama, he says further actions in Iraq by America "will result in the bloodshed of your people".

After the victim is apparently beheaded, another man, said to be journalist Steven Joel Sotloff, who went missing near the border of Syria and Turkey last year, is shown at the end of the video, with the IS fighter saying his life depends on President Obama's "next decision".

A message posted on a Facebook page called "Free James Foley" last night read: "We know that many of you are looking for confirmation or answers. Please be patient until we all have more information, and keep the Foleys in your thoughts and prayers."