The United Nations on Thursday launched a $2.2 billion (1.7 billion euros) appeal to assist 5.2 million people who need protection and assistance in conflict-torn Iraq.
"The needs of the Iraqi people are immense," Neill Wright, the UN's acting humanitarian coordinator for Iraq, said in Baghdad.
The UN's revised response plan said there are 1.8 million displaced people nationwide, 1.5 million in the communities hosting the displaced and 1.7 million people living in conflict areas outside of government control who need help.
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"An estimated 2.8 million people are in need of food assistance and approximately 800,000 people are in urgent need of emergency shelter assistance," a UN statement said.
Many of the hundreds of thousands who fled successive waves of violence this year, mostly perpetrated by the Islamic State jihadist group, have found refuge in autonomous Kurdistan.
Winter temperatures in the mountainous region can range from 5 to -16 Celsius (40 to 0 Fahrenheit) and the UN has repeatedly voiced alarm at the fate of many displaced who still have no shelter.
In addition to the 1.8 million displaced, the UN stressed there were more than 200,000 Syrian refugees on Iraqi soil, as well as an estimated one million Iraqis previously displaced due to violence over the past decade.
Previous appeals for Iraq and neighbouring Syria, where even more people have been forced from their forces, have been under-funded.