IS extremists guilty of war crimes

Residents of Tabqa city and Islamic State militants tour the streets in celebration after IS took over Tabqa air base. Picture: Reuters

The report by UN human rights chief Navci Pillay said crimes included mass executions of prisoners, slavery, sexual attacks and “ethnic and religious cleansing”.

The persecution of entire communities and systematic violations by the al-Qaeda offshoot have been documented by UN human rights investigators.

Her statement came as London mayor Boris Johnson provoked a row by claiming that those returning from Iraq who had been there “for no good reason” should be detained.

The crisis also saw the Assad regime in Syria making advances to the West to co-operate in fighting IS, after the US suggested it might extend its air attacks on the Islamic extremists into Syria.

In her statement, Ms Pillay described “grave, horrific human rights violations [that] are being committed daily by IS and associated armed groups”.

She cited targeted killings, forced conversions, abductions, slavery, sex crimes, forced recruitment and destruction of places of worship.

“They are systematically targeting men, women and children based on their ethnic, religious or sectarian affiliation and are ruthlessly carrying out widespread ethnic and religious cleansing in the areas under their control.”

Christians, Yazidis and Turkmen were among the minorities targeted by the Sunni militant group, which has forced people to convert to their strict form of Sharia law, she said.

Meanwhile, Deputy Prime Minister Nick Clegg has rejected calls for tougher measures to combat the threat posed by British jihadists returning from Iraq and Syria, saying that a new law would not remove the danger from IS extremists.

Mr Clegg said he would listen to what the police and intelligence services said they needed to tac