The UN has declared its highest level of emergency in Iraq as a humanitarian crisis follows the rapid advance by Islamic State militants in the north.
Kurdish officials said the situation in Dohuk city, with 150,000 refugees, was now critical.
But the US said a rescue mission to aid thousands who fled to Mt Sinjar was unlikely as it had found fewer people and better conditions than expected
The UN estimates that 1.2 million Iraqis have been internally displaced.
The three other countries that have the same emergency status are Syria, South Sudan and the Central African Republic.
The declaration by the UN of a “Level 3 Emergency” would “facilitate mobilisation of additional resources in goods, funds and assets to ensure a more effective response to the humanitarian needs of populations affected by forced displacements,” said UN special representative Nickolay Mladenov.
The situation of displaced people on Mount Sinjar remained critical, he said.
The UN had estimated that tens of thousands of people, most from the Christian and Yazidi religious minorities, were besieged on the mountain after being forced to flee their homes.
