Amidst differences between ruling coalition partners on ways to deal with the ISIS challenge, six British Muslim scholars have issued a 'fatwa' opposing the group's 'poisonous ideology' and prohibiting the youth from joining it in Iraq and Syria.
Prime Minister David Cameron is scheduled to outline new measures on Monday, including preventing British citizens who travel abroad to participate in extremism from re-entering the country.
Leading figures of coalition partner Liberal Democrats criticised Cameron's 'kneejerk' reaction to the ISIS challenge while Tory ministers insisted that the threat to Britain was 'very real'. Britain last week raised the terror threat level to 'severe'.
The Sunday Times reported that the Muslim scholars have condemned British Muslims fighting alongside ISIS extremists in Iraq and Syria. The 'fatwa' prohibits would-be British jihadists from joining "oppressive and tyrannical" ISIS.
In a 'fatwa' considered first of its kind in Britain, the six imams from Manchester, Leeds, Leicester, Birmingham and London have ordered all Muslims to oppose ISIS' "poisonous ideology" , especially when it is promoted within Britain.
The 'fatwa' has been issued following criticism that British Muslim leaders have not done enough to condemn aspiring jihadists who have travelled to fight for Isis, or those supporting its ideology in the UK, the report said.
It says: "British and other EU citizens are bound by their duties to their home countries according to Islamic theology and jurisprudence: it is therefore prohibited (haram) to travel to fight with any side in Syria."
The 'fatwa' was written by Sheik Usama Hasan, a former imam at the Masjid Al-Tawhid Mosque in east London.
Mufti Abdul Kadir Barakatullah, a member of the UK Shariah Council, said: "We oppose ISIS, and anybody who is supporting Isis will see our position," he said. "Fighting is only exacerbating and prolonging the suffering."
Jack Straw, the former Labour home secretary whose Blackburn seat has a large Muslim population, welcomed the statement: " The medieval barbarity of ISIS and its ilk is completely contrary to Islam. It's crucial that members of the faith find their voice to condemn their apostasy."