Speaking to reporters in New York, the Spokesperson for the UN Secretary-General said that some 360,000 people are believed to be caught between the fighters.
They are providing emergency response packages with basic food, water and hygiene items. Some 2.6 million people have received aid since October.
The UN and partners is trucking 3.1 million litres of water per day into eastern Mosul to meet water shortages. That figure was about 2.3 million litres at the end of April.
In addition to aid, the UN is concerned about the high trauma and casualty rates.
Since 17 October, health care partners report over 12,000 people have been referred to hospitals in Mosul and neighbouring governorates, and nearly half of these reported cases were from west Mosul only, Mr. Dujarric said.
The UN Office for the Coordination of Humanitarian Affairs (OCHA) has said that new field hospitals have also been created, one for emergency reproductive and obstetric healthcare.
