The U.N. human rights chief told the Security Council on Friday that in a "most terrible irony," the Islamic State group may be more accepting of the ethnic diversity of its members than some states are about ethnic differences among their own citizens.

Zeid Raad al-Hussein, the first human rights chief from the Muslim and Arab worlds, spoke as French Foreign Minister Laurent Fabius chaired a special meeting on the abuses in the Middle East on ethnic and religious grounds. Both said the Security Council should refer the situations in Iraq and Syria to the International Criminal Court, and Zeid said the council should take unanimous action to end both conflicts.

Zeid called the Islamic State group "an abomination" but also criticized states in the Middle East and elsewhere for overlooking abuses, attacking civil society and letting fanaticism flourish. "If we attend to minority rights only after the slaughter has begun, then we have already failed," he said.

The rights chief, who is from Jordan, did not name any governments in his criticism. He said the Islamic State may be more accepting of ethnic diversity of its members so long as they adhere to the group's world view, even while the "intricately interwoven social fabric in Syria and Iraq is giving way to the demented obliteration of any difference" from IS ideology.

The Islamic State group has seized large parts of Syria and Iraq over the past year, drawing an international military response that includes U.S. airstrikes against the extremists in both countries. The group has imposed a harsh version of Islamic law and beheaded and massacred their opponents.

"Ordinary citizens are wondering how so many countries gathered here together, who call themselves the 'United Nations,' have so far been unable to tackle terrorism and eradicate it," Fabius said.

U.N. Secretary-General Ban Ki-moon also urged the council to act to protect civilians and end impunity in Syria's four-year conflict in particular but stopped short of mentioning the ICC.

Zeid reminded council members that earlier this month, his office found that the Islamic State group's vicious attacks on Iraq's minority Yazidi community "may amount to genocide." The report details killings, torture, rape and sexual slavery, forced religious conversions and the conscription of children.