British IS extremists 'most vicious fighters'

British extremists are amongst the "most vicious and vociferous fighters" in the Islamic State's (IS) ranks in Syria and Iraq, a jihadism expert has said after a video purporting to show a US journalist James Foley being beheaded by a British-accented IS fighter was placed online.

Shiraz Maher, from King's College London's International Centre for the Study of Radicalisation, told the Today programme: "Unfortunately the British participation in the conflicts now raging in both Syria and Iraq has been one of full participation, one that has seen them at the front lines, taking part in the conflict in every way."

He added: "The way the Foley video was framed makes it very clear now that ISIS (the former name of the IS) will react against any Western involvement or intervention."

First broadcast on BBC Radio 4's Today programme on Wednesday 20 August.