LONDON: “Jihadi John”, the masked Islamic State group militant apparently responsible for beheading a series of Western hostages, was named on Thursday as Kuwaiti-born London computer programmer Mohammed Emwazi.

A Washington Post report citing friends, a leading think-tank researching foreign militants and a British security official quoted by the New York Times identified Emwazi as being the executioner.

The International Centre for the Study of Radicalisation at King's College in London said it believed the identity “to be accurate and correct”.

“We're pretty confident that the right individual has been named,” Shiraz Maher, a senior research fellow at the centre, told AFP.

He believed the leak had come from the United States and pointed out that “there are no further Americans being held hostage by Islamic State”.

“I think the US chose to put this out,” he said.

London's Metropolitan Police dismissed the reports as “speculation” and said it was “not going to confirm his identity” to protect human lives.

Cage, a civil rights group that was in contact with Emwazi for several years over his alleged harassment by British security services, said that while not 100 per cent certain, they believed it was him.

“Jihadi John”, nicknamed after Beatle John Lennon due to his British accent, is believed to be responsible for the murders of US journalists James Foley and Steven Sotloff, British aid workers David Haines and Alan Henning and American aid worker Abdul-Rahman Kassig.

He also appeared in a video with Japanese hostages Haruna Yukawa and Kenji Goto shortly before they were killed.

In the videos posted online, he appears dressed all in black with only his eyes exposed, brandishing a knife while launching tirades against the West.

Haines's daughter Bethany told ITV News that her family and those of other victims would “feel closure and relief once there's a bullet between his eyes.”

Stylish and polite

Cage's research director Asim Qureishi described Emwazi as a “beautiful young man” who had been alienated by his treatment at the hands of the British security services.

Cage published correspondence with Emwazi in which he alleged that a British MI5 secret service agent named “Nick” tried to recruit him while interrogating him at Amsterdam's Schiphol Airport in 2009.

Emwazi said he was returning with two friends after they were expelled from Tanzania, accused of trying to join militants in Somalia but on a trip that he claimed was a safari holiday after finishing university.

“Why don't you work for us?” Emwazi quoted “Nick” as telling him. After refusing, he said the officer told him: “You're going to have a lot of trouble, you're going to be known, you're going to be followed. “After being refused entry to Kuwait three times, Cage said Emwazi left his London home in 2013 and that four months later, police told his family he had entered Syria.

The emails appear to point to growing radicalisation -- he finished one in 2010 saying: “May Allah get rid of the oppressors i.e. security agents”.

Masked killer known as "Jihadi John".-Reuters

Ideology, not poverty

Emwazi, said by Cage to be 26, was identified to the Post by friends and others familiar with the case, with one acquaintance telling the paper: “I have no doubt that Mohammed is Jihadi John”.

The US National Security Council said in a statement that it would neither confirm nor deny the reports. Emwazi is from a middle class family and earned a degree in computer programming.

Dozens of reporters gathered outside a modern property believed to belong to his family in the northwest London neighbourhood of Queen's Park.

Qureishi said the family did not believe the allegations against their son and were in a state of “absolute shock”. The University of Westminster said in a statement that it had a record of a Mohammed Emwazi leaving college six years ago and was setting up a pastoral team to provide advice and support to students.

“If these allegations are true, we are shocked and sickened by the news. Our thoughts are with the victims and their families,” it said.

Emwazi is described as being quiet and polite with stylish dress sense. In one email to Cage, he complained about police going through his designer clothes.

The rights group claimed that Emwazi had “desperately wanted to use the system to change his situation but the system ultimately rejected him. “Maher said Emwazi's middle-class background belied the conventional wisdom “that terrorism is driven by people from socially deprived backgrounds”.

He predicted that his apparent unmasking would deal a “psychological blow “to the IS group.

“They'll feel somewhat deflated that someone they wanted to preserve and protect as an asset has been outed in this way but it won't change anything day to day,” Maher added.

British intelligence officers estimate that there are around 700 homegrown militants fighting for IS in Syria and Iraq.