'Security services systematically harassed young Muslims'

Reports out of America claim the masked militant, identified by journalists as computer programming graduate Mohammed Emwazi from London, had been approached by MI5 to act as an informer before shunning them and leaving for Syria.

Campaigners with the Cage organisation - which lobbies against the US-led war on terror - said it had been in contact with Emwazi for two years over alleged "interference" by the UK security agencies.

Cage said British security services "systematically" harassed young Muslims, leaving them with no legal avenue to redress their situation, citing the example of Michael Adebolajo, who murdered soldier Lee Rigby in May 2013.

Cage director Asim Qureshi said: "Like Michael Adebolajo, suffocating domestic policies aimed at turning a person into an informant but which prevent a person from fulfilling their basic life needs would have left a lasting impression on Emwazi.

"He desperately wanted to use the system to change his situation, but the system ultimately rejected him."

Cage describes itself as an "independent advocacy organisation" working for more than a decade to empower communities impacted by the war on terror.

Its work has focused on working with survivors of abuse and mistreatment across the globe.

Cage says the war on terror, prompted by the Western response to 9/11, has been used "to justify the invasion and occupation of countries, often to further other agendas".

It is opposed to the Guantanamo Bay detention camp, and is also critical of the UK's terrorism policy.

Of the latter, it has said: "Prejudice, ill-information and even fabricated accounts of terrorist acts produced through forced or coerced confessions have been the basis to justify a whole raft of anti-terror legislation and illegal/immoral actions in the United Kingdom."

Speaking at a press conference today, Mr Qureshi criticised the UK's domestic security strategy since 9/11, which he said had only increased alienation.

He said: "When are we going to finally learn that when we treat people as if they're outsiders they are going to feel like outsiders and they will look for belonging elsewhere."

"Jihadi John" is believed to be involved in the murders of American journalist James Foley, US journalist Steven Sotloff, British aid workers David Haines and Alan Henning, and American aid worker Peter Kassig.

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