International human rights lawyer Amal Clooney and a young Yazidi woman who was enslaved and raped by Islamic State fighters pushed Iraq on Thursday, March 9 to allow a United Nations investigation into crimes by the militant group, Reuters reports.

Britain is drafting a United Nations Security Council resolution to establish a UN investigation, but Clooney said the Iraqi government needs to send a letter formally requesting the inquiry before the 15-member council can vote.

Islamic State is committing genocide against the Yazidis in Syria and Iraq to destroy the minority religious community through killings, sexual slavery and other crimes, UN experts reported in June last year.

Clooney, who represents Nadia Murad and other Yazidi victims of Islamic State, said that despite public support by Iraq for a UN investigation, the government has not yet made a request.

"We do want to see an investigation take place with the cooperation of the Iraqi authorities," Clooney told Reuters in an interview after speaking at a United Nations event on accountability for crimes committed by Islamic State.

"But ultimately if that support is not forthcoming in terms of real action, then the UN has to think of other ways in which to achieve accountability," she said.

The Yazidis are a religious sect whose beliefs combine elements of several ancient Middle Eastern religions. Islamic State militants consider the Yazidis to be devil-worshippers.