The Islamic State militant known as "Jihadi John" has been identified as a Londoner called Mohammed Emwazi, it has been reported.

According to The Washington Post, Emwazi comes from a well-to-do family and graduated from college with a degree in computer programming.

He is believed to have travelled to Syria around 2012 and to have joined the Islamic State later.

"Jihadi John" is the name that has been given to a masked man with a British accent, who has been seen in several videos of hostages being murdered.

A man claiming to be a close friend of Emwazi told the newspaper: “I have no doubt that Mohammed is Jihadi John. He was like a brother to me... I am sure it is him.”

A representative of a British human rights group who had been in contact with Emwazi before he left for Syria also said he believed he was "Jihadi John".

Emwazi is said to have been identified by US authorities in September, a month after he featured in a video killing American journalist James Foley.

Since then he has appeared in a series of videos documenting the gruesome murders of other hostages, including British aid workers Alan Henning and David Haines.

In each, he taunts audiences and is dressed in all black, with a balaclava covering his face. He wears a holster under his left arm.

Last month, Emwazi appeared in a video with the Japanese hostages Haruna Yukawa and Kenji Goto, shortly before they were killed.

Reaction

A spokeswoman for the British Embassy in Washington said: "(The) Prime Minister has been clear that we want all those who have committed murder on behalf of ISIL (Islamic State) to face justice for the appalling acts carried out.

"There is an ongoing police investigation into the murder of hostages by ISIL in Syria. It is not appropriate for the Government to comment on any part of it while this continues.”

Downing Street declined to confirm or deny if Emwazi's name was known to the intelligence and security services.

Asked if David Cameron was concerned about him being identified, a spokeswoman said: "The Prime Minister would be concerned about information being put into the public domain at any time that might jeopardise ongoing police or security investigations or the safety of British citizens."

A statement from the International Centre for the Study of Radicalisation at King's College London said: "We believe that the identity and name published by the Washington Post and now in the public realm to be accurate and correct."

The statement added: "This demonstrates what we have long said about radicalisation, that it is not something driven by poverty or social deprivation. Ideology clearly plays a big role in motivating some men to participate in jihadist causes."

Professor of National Security Studies John Gearson thinks security officials are being cautious:

Asim Qureshi from human rights group CAGE had been in contact with Emwazi before he is believed to have traveled to Syria.

He finds it hard to tally videos appearing to show him beheading hostages with the man he knew:

Originally posted at 11.42am