A group of UK faith leaders have united to urge David Cameron to challenge and hold to account the Islamic State (IS) for its violations of humanitarian laws.
"Such violations as are currently taking place are crimes against humanity that must be both stopped and punished," a letter, signed by Christian, Muslim, Jewish, Hindu, Sikh and Zoroastrian leaders, to the Telegraph reads.
"The culture of impunity within which these dehumanising atrocities have been committed needs to be challenged most vigorously. Given that Iraq is not a state party to the International Criminal Court, the Government must now work towards a United Nations Security Council Resolution that refers this matter to the International Criminal Court for investigation and where necessary prosecution.
"The international community must send a clear signal of intent to those who are committing such atrocities that at some point they will be held accountable for their actions," the signatories insist.
IS militants are attempting to form a caliphate across a stretch of Syria and Iraq and have become notorious for their extreme violence. Reports suggest they have crucified and beheaded Christians and Yazidis, who they consider to be enemies of the Islamic State.
On Tuesday, a video was posted online showing US journalist James Foley being beheaded by an IS fighter, who is thought to be a British jihadist.
The graphic video bears the title: 'A Message to America'.
Prime Minister David Cameron yesterday condemned Foley's fate as a "barbaric and brutal act...an act of murder, and murder without any justification," and promised that "even tougher laws" will be brought in to combat terrorism.
The Prime Minister added that "far too many British citizens have travelled to Iraq and travelled to Syria to take part in extremism and violence. And what we must to is redouble all our efforts to stop people from going...and do everything we can to keep our people safe. And that is what this Government will do."
In their letter, the faith leaders – led by the Rt Rev Christopher Cockworth, Bishop of Coventry – warn that the hideous crimes committed by IS militants are "a tragedy of historic proportions".
The "gross and systematic" persecution of religious minorities is a growing issue globally and must be stopped, the letter adds.
"These violations are sadly part of a wider global pattern of increased societal hostility and government restrictions against freedom of religion or belief.
"Governments, international institutions and Non Governmental Organisations need to recognise this wider crisis and commit the necessary time, energy and resources to ensure greater respect for this fundamental freedom in order to attempt to forestall such further tragedies."
Other signatories include the Roman Catholic Bishop of Clifton, Rt Rev Declan Lang, as well as leaders from the Coptic Orthodox and Greek Orthodox Churches.
The secretary of the Muslim Council of Britain also signed the letter, along with Jewish Rabbis, the secretary general of the Hindu Forum of Britain and the president of the Zoroastrian Trust Funds of Europe.