“The numbers of people fleeing their homes in western Mosul are overwhelming,” said Humanitarian Coordinator for Iraq Lise Grande in a press release from the UN Office for the Coordination of Humanitarian Affairs (OCHA).

Since military operations against the Islamic State in Iraq and the Levant (ISIL/Da'esh) began in Mosul seven months ago, nearly 700,000 people have been displaced, including 500,000 people from the city's western neighbourhoods.

Iraqi Security Forces have made rapid gains in north-west Mosul and ISIL terrorists are reportedly surrounded in the west of the city.

“The military battle in Mosul isn't over yet and even when it is, the emergency will continue for months… Hundreds of thousands of lives are at stake,” said Grande, stressing the need to re-double efforts to mobilize more resources to assist the people in need.

She said many are lacking food and haven't had access to safe drinking water and medicines for weeks or months.

Acknowledging the generosity of people in other parts of Mosul who are opening their homes for displaced families, she said: “Without this support, the camps would have been overwhelmed long ago.”

To date, the $985 million appeal for Iraq is less than 30 per cent funded. About $331 million is being sought for the Mosul assistance.