United Nations: The campaign of Islamic State militants against Iraq`s Yazidi minority may be attempted genocide, UN Assistant Secretary-General for human rights Ivan Simonovic said on Tuesday.

"Facts are indicating that actions against Yazidis may amount to attempted genocide," he told a small group of reporters at the United Nations after returning from a recent visit to Iraq.

Simonovic was speaking as Islamic State, often referred to as ISIL or ISIS, advanced on Iraq`s Sinjar mountain, tightening a siege of thousands of stranded Yazidis, who called on the United States and its allies to act to avert more bloodshed.