More than 300,000 people have fled Mosul since the start of the US-backed campaign in October, the office of the UN Humanitarian Coordinator in Iraq said in a statement.
Mosul had a pre-campaign population of about a million and half, split more or less evenly between the sides lying east and west of the Tigris river that runs through the middle.
Iraqi forces captured the eastern side in January and in February launched a second phase to take the western side, with air and ground support from a US-led coalition.
They are now battling to take the northwestern part, but the civilian death toll has mounted in the densely populated Old City, where the militants are dug in among residents.
More people are expected to flee the fighting and camps for the displaced north and east of Mosul are expanding, the UN statement said.
Airstrikes on the city by the Iraqi air force resumed on Tuesday as the sky cleared after several days of bad weather, the Iraqi military said.
A number of Daesh commanders were killed in an airstrike on a position in Hay Al-Tanak, a stronghold of the group in the west of Mosul, the Iraqi military said in statement.
Among those killed were commanders in charge of booby traps, of Arab suicide fighters and child recruitment, the statement added, without identifying them by name.
Daesh media outlets did not mention the strike.
The improved weather should also allow ground forces to resume their advance toward the Grand Al-Nuri Mosque, where the militants’ leader, Abu Bakr Al-Baghdadi, declared a “caliphate” nearly three years ago over parts of Iraq and Syria.
The current phase of the campaign is the most difficult as narrow alleyways in the densely populated old city limit the use of artillery, air power and armored vehicles.
An explosion in western Mosul last month killed between 60 and 240 people, according to various accounts.-ARAB NEWS