UK & World News
International Manhunt For 'John' The IS Killer
Counter-terrorism police in the UK say they are investigating the English-accented Islamic State fighter who beheaded journalist James Foley.
In a video posted by the militant group to social media sites, the man speaks English and blames US airstrikes for the killing of the 40-year-old American.
The killer, who is clad in black and covers his face during the video, speaks with a southeastern English accent, appears to be left-handed and is of average height.
The man has reportedly been identified as one of a group of Britons holding foreign hostages in Syria.
Speaking to Sky News, the Guardian's Martin Chulov said the man called himself "John", and was the leader of several Britons who guard prisoners in the Islamic State stronghold of Raqqa.
"We spoke to a hostage today who was released several months ago and he clearly identified to us this man in the video," Mr Chulov said.
"He identified him as a British national, one of three British nationals who were responsible for guarding foreign prisoners in Raqqa.
"He was the leader of the pack, someone who was very assertive and was responsible for negotiations with hostage families and certainly had spoken to many mums, dads, (and) wives on Skype."
Mr Chulov said the man is likely to have been fighting with IS for at least a year.
"These are not newcomers. These guys have been around for quite some time - at least a year, and potentially 18 months.
"Throughout that time they had a leadership role in terms of guarding the foreign prisoners in Raqqa, all of whom had become very valuable to the Islamic State organisation.
"The fact that this British national speaks such fluent English, he writes fluent English as well, he has been given a lot of trust and authority within the jihadist structure in Raqqa."
The Metropolitan Police Service Counter Terrorism Command said it is investigating the video.
It added: "We would like to remind the public that viewing, downloading or disseminating extremist material within the UK may constitute an offence under Terrorism legislation."
At least 400 people are known to have travelled from the UK to Syria and Iraq to fight for Islamic State (IS) - formerly known as Islamic State in Iraq and Syria (ISIS).
Concerns have been raised that radicalised young men from Western countries will return to their home nations and could be used to carry out attacks.
Sky's Middle East Correspondent Sherine Tadros said: "We know that around 400 British nationals have joined IS, probably more than that in the last few months as their recruitment has gone into overdrive.
"Now they are being used in these more serious videos to try to pressure foreign governments - and also people in these countries - to try to pressure their governments not to intervene."
Security agencies, including the FBI and MI5, will be tracking those who have travelled to Iraq and Syria to join the militant organisation.
A Home Office spokesperson added: "The police and security services are actively working to detect and disrupt terrorist threats.
"People seeking to travel to engage in terrorist activity in Syria or Iraq should be in no doubt we will take the strongest possible action to protect our national security, including prosecuting those who break the law.
"We also have a wide range of powers at our disposal to disrupt travel and manage the risk posed by returnees."
Radicalisation expert Shiraz Maher told Sky News that Britons were at the "forefront" of the IS conflict and were "not taking a back seat" in the violence.
Crawley father-of-three Abdul Waheed Majeed, 41, became the first Briton suspected of staging a suicide bomb attack when he attacked a jail in Aleppo in February.
In May, 18-year-old Abdullah Deghayes, from Brighton, was killed while fighting in Syria alongside his two brothers Jafar and Amer.