Another 200,000 people may flee their homes as the fighting in the northern Iraqi city of Mosul intensifies, the United Nations has said.
UN humanitarian co-ordinator Lise Grande said nearly 700,000 people have already been displaced from Mosul since US-backed Iraqi forces launched a major operation in October to retake the city from Islamic State (IS).
Iraqi forces have driven the militants from most of Mosul, but are still battling them in densely populated western districts.
Ms Grande said: "The numbers of people fleeing their homes in western Mosul are overwhelming.
"They are fleeing under very difficult circumstances. Many are food insecure and haven't had access to safe drinking water and medicines for weeks or months."
The Iraqi government and humanitarian aid agencies are rushing in supplies, she said, but because of the large number of displaced "it's becoming more and more difficult to ensure civilians receive the assistance and protection they need".
IS captured Mosul in the summer of 2014 when it swept across northern and central Iraq. Iraqi forces have taken most of that territory back in recent years with the help of a US-led air campaign.