Muslim leaders have issued a fatwa condemning UK citizens who fight for extremists in Iraq and Syria, British media reports say.
The fatwa, comes as the strongest denunciation yet, by the muslim community, of UK citizens who join militants of the self-proclaimed Islamic State, formerly known as ISIL and ISIS, The Sunday Times reported.
Meanwhile, Liberal Democrat leader Paddy Ashdown accused Conservative ministers of "kneejerk" responses to the terrorism threat from extremists even as the US carried out airstrikes against IS fighters near Amerli in northern Iraq.
Air drops were also made to civilians in the area, which included two by British Hercules aircraft, as the Iraqi army evacuated people from the besieged town with Iraqi and Kurdish forces closing in on IS fighters.
The UK government escalated the terror threat level to the UK from "substantial" to "severe", although according to home secretary Theresa May there was no evidence to suggest an attack was "imminent".
A fatwa is an edict concerning any aspect of Islamic life and is issued by a learned muslim scholar, which cannot be revoked and dies only with the person it is imposed on.
According to report, six senior Islamic scholars had endorsed the fatwa, describing UK citizens allied to Islamic State cells as "heretics".
According to a report in The Guardian , the IS had established a sophisticated publicity arm that tapped into popular culture. It said the group posted on Twitter (the account is currently suspended), post pictures of fighters with kittens, upload videos of their actions on YouTube and so on.
It said these were savvy, global broadcasts aimed at drawing a reaction from a global audience and were calculated to give young radicalised muslims a sense of power and draw from their sense of injustice.
The Australian government said last week that it would spend A$64 million on measures to counter violent extremism and radicalisation as the Islamic State (IS) continued to recruit foreign fighters to its ranks in Iraq and Syria.
Australian Prime minister Tony Abbott said, ''This [Islamic State] is a movement - as we've seen on our TV screens and front pages of our newspapers - of utter ferocity, medieval barbarism allied to modern technology - that's how serious and dangerous this movement is.''