UN rights monitors called Tuesday for the global community to take urgent action to avoid a potential genocide against the Yazidi community in Iraq.
Thousands of members of the Yazidi religious minority are trapped on a mountain in northwestern Iraq with little food or water after Islamic State jihadists overran the region.
"All possible measures must be taken urgently to avoid a mass atrocity and potential genocide within days or hours," said UN minority rights expert Rita Izsak.
"Civilians need to be protected on the ground and escorted out of situations of extreme peril," Izsak said in a joint statement with fellow monitors, urging action by the Iraqi government and international community.
Thousands of Yazidi refugees are stranded on Mount Sinjar, besieged by Sunni extremists from the Islamic State who control much of northern Iraq and eastern Syria.
"We are witnessing a tragedy of huge proportions unfolding, in which thousands of people are at immediate risk of death by violence or by hunger and thirst," said Chaloka Beyani, UN monitor on refugee rights.
"Humanitarian aid must be delivered quickly and no efforts should be spared to protect all groups forcefully displaced by this conflict."
UN refugee agency spokesman Adrian Edwards told reporters there were 20,000-30,000 people on Sinjar Mountain.
World Health Organization spokesman Paul Garwood said two medical teams had reached the mountain, while supplies had been sent in by helicopter.
The United States and France have also dropped aid supplies.
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Edwards said some 35,000 people had managed to flee the mountain, head into Syria and then reach Iraqi Kurdistan.
"The new arrivals are exhausted, dehydrated and many have suffered sun or heat stroke, with the daily temperatures reaching 40 to 45 degrees Celsius (101 to 113 degrees Fahrenheit)," he said.
- 'Attempted extermination' -
Kurdistan's Dohuk governorate has taken in hundreds of thousands of people driven from their homes by the offensive, including Yazidis, Christians, Shabak, Kakai, Armenian and Turkmen minorities, Edwards said.
The UN is rushing in supplies, he said, applauding locals for helping the refugees.
In all, there are more than 1.2 million internally displaced people in Iraq, including 700,000 in Kurdistan, which was already hosting 220,000 Syrian refugees.
Another 10,000 to 15,000 Yazidis have opted to flee to war-torn Syria.
Islamic State fighters have presented non-Muslims with a "convert or die" option, said Christof Heyns, UN expert on arbitrary executions.
"We cannot stand by in the face of such atrocities. International actors must do all in their power to support those on the ground with the capacity to protect lives," he said.
Religious rights monitor Heiner Beilefeldt said freedom of faith was being "denied in the most gross and systematic way possible, through the attempted extermination of religious minorities."
Women are bearing the brunt, warned Rashida Manjoo, who monitors gender-based violence.
"We have reports of women being executed and unverified reports that strongly suggest that hundreds of women and children have been kidnapped –- many of the teenagers have been sexually assaulted, and women have been assigned or sold to 'IS' fighters," she said.