An IS thug grips Steven Sotloff by the collar in chilling video which featured threats to murder US reporter
The Isis militant who brutally murdered James Foley is one of between 400 and 500 Brits believed to be fighting in Iraq and Syria.YouTube

The former head of counter-terrorism at MI6, Richard Barrett, has said Britons who have travelled to Syria or Iraq to join jihadist group Isis (Islamic State) should be helped to reintegrate to life in the UK when they return.

Barnett also said that jihadist fighters who come back to the UK after fighting alongside Islamic State could "be very useful in preventing further radicalisation" among other Brits.

He told BBC Radio 4's Today programme that returning militants could have valuable information on why people went to the region, which could be used to prevent others from travelling to the war zone.

"They will be of enormous help, or could be, in helping to build the resilience of vulnerable communities to the sort of radicalising message which are all too easily available on social media," he said.

Between 400 and 500 British men are believed to have left their homes to fight alongside Isis in Syria or Iraq, the UK Foreign Office has revealed.

British Isis members have faced increasing scrutiny in recent weeks following the brutal execution of US journalist James Foley by a man believed to be from London.