Actions of militants of the Islamic State group in Iraq’s Sinjar mountains “may amount to attempted genocide,” the United Nations said on Tuesday, referring to the ISIS onslaught in the region that has so far led to the deaths of thousands people belonging to the minority Yazidi community, according to media reports.

“The evidence strongly indicates an attempt to commit genocide,” the U.N. Assistant Secretary-General for Human Rights Ivan Simonovic reportedly said in Geneva on Tuesday, after returning from a recent trip to Iraq. He added that the only options being given to the Yazidis are “to convert or be killed."

Simonovic also said that he had met at least 70 Yazidis, many of whom had escaped sexual slavery, in Baghdad, and the Iraqi cities of Erbil and Dohuk during his trip.

The Yazidis, who have historically lived primarily around the Sinjar mountains in Iraq’s northern Nineveh province, have been subject to several attacks from the Islamic State group since June. The Sunni extremist group has branded the Yazidis, whose religious practices resemble an ancient form of Zoroastrianism, as “devil worshippers.”

In an article published in the ISIS propaganda magazine Dabiq earlier this month, the group claimed that it has enslaved several Yazidi women and children in villages near Sinjar and sold them to its members fighting in the region.

Tens of thousands of Yazidis have been forced to flee the onslaught of the Islamic State group and those remaining have been forced to convert to Islam, according to media reports.