Islamic State is still committing genocide against the Yazidi minority in Iraq after three years but the world is failing in its duty to punish the crime, the U.N. Commission of Inquiry on Syria said on Thursday.

"The genocide is on-going and remains largely unaddressed, despite the obligation of States...to prevent and to punish the crime," the commission said.

"Thousands of Yazidi men and boys remain missing and the terrorist group continues to subject some 3,000 women and girls in Syria to horrific violence including brutal daily rapes and beatings."