More than 140,000 Iraqis have fled parts of Anbar province over clashes between security forces and al Qaida militants, the worst displacement of civilians in years, the UN says.
It was "the largest" displacement witnessed in the country since the sectarian violence of 2006-2008, said he spokesman for the UN High Commissioner for Refugees, Peter Kessler, said more than 65,000 people fled the conflict just in the past week alone.
Since late December, members of Iraq's al Qaida branch - known as the Islamic State of Iraq and the Levant - have taken over parts of Ramadi, the capital of the largely Sunni province of Anbar. They also control the centre of the nearby city of Fallujah.
Mr Kessler said that many civilians are trapped and suffer from a lack of supplies.
"Many civilians are unable to leave conflict-affected areas where food and fuel are now in short supply," he said.
Some displaced families have ended up in abandoned buildings, schools and half-built houses while others stay with relatives. International aid agencies appealed to the warring parties on Wednesday to allow humanitarian aid to reach those affected.