Tens of thousands of civilians remain trapped by militants on a mountain in northern Iraq and need "life-saving assistance", the United Nations has warned.
Members of the Yazidi sect fled there 10 days ago after fighters from Islamic State (IS) seized the town of Sinjar, according to the BBC.
US air strikes continued on Tuesday, with a drone targeting an IS mortar near Kurdish troops, the Pentagon said.
IS fighters have seized large swathes of northern Iraq and Syria in recent months, forcing tens of thousands of people from religious minorities to flee their homes.
UN Secretary-General Ban Ki-Moon urged countries to do more to help Iraqi civilians.
"The plight of Yazidis and others on Mount Sinjar is especially harrowing," he said.
Britain has announced it will send Chinook helicopters to help the refugees.
An estimated 20,000 to 30,000 people remain trapped on Mount Sinjar without food, water or shelter said the UN's Adrian Edwards in a statement.
There are now an estimated 1.2 million internally displaced Iraqis, he added.
Keiran Dwyer, who works for the UN's office for humanitarian affairs in Irbil, told the BBC that some Yazidis had managed to escape from the north side of the mountain in the last 72 hours and cross the River Tigris into Syria, where they were receiving help.
But a Yazidi relief worker, who was on board an Iraqi Air Force helicopter evacuating the trapped refugees, described the situation as "a genocide" and said that he had seen what looked like "hundreds" of dead bodies on the ground.
"You can imagine what it's like when you land amongst 5,000 people and can only take 10 or 20, and everybody tries to get on the helicopter," Mirza Dinnay told the BBC.
The Iraqi prime minister Nouri al-Maliki on Tuesday ordered Iraq's security forces to stay out of the political crisis over who will form the next government, amid fears they could intervene.
Earlier, special forces, police and soldiers loyal to Mr Maliki had deployed around strategic installations in Baghdad.
A member of Mr Maliki's Dawa Party, Haidar al-Abadi, has been tasked with forming Iraq's next government, but Mr Maliki is insisting the job should be his.
However, his rival has gained widespread international support, most importantly from Washington and Tehran.