“Our worst case scenario when the fighting started was that up to one million civilians may flee Mosul. Already, more than 493,000 people have left, leaving almost everything behind,” Lise Grande, the Humanitarian Coordinator for Iraq, said in a news release issued by the UN Office for Coordination of Humanitarian Affairs (OCHA).

“The sheer volume of civilians still fleeing Mosul city is staggering […] we are doing everything we can but this has been a long battle and the assault on the old city hasn't started,” she added.

According to estimates, as many as 500,000 people still remain in ISIL-controlled areas in western Mosul, including about 400,000 in the densely populated old city.

Humanitarian agencies are scaling up their response, preparing emergency sites and camps to shelter the hundreds of thousands more who may flee in coming days and weeks, but they are under increasing strain.

Since the fighting began last October, some 1.9 million people have been provided live-saving assistance, including food, water, shelter, emergency kits, medical support and psycho-social services, since fighting began last October.

“We're reaching families who have fled and families who have stayed [but] Mosul has pushed us to our operational limits,” said the Humanitarian Coordinator.

'Nothing is more important than protecting civilians – nothing'

The battle for western Mosul is very different from the one in the east and so is the consequent impact on civilians. More trauma injures are reported and there are fears that food stocks and drinking water could run out.

“Civilians in Mosul face incredible, terrifying risks. They are being shot at, there are artillery barrages, families are running out of supplies, medicines are scarce and water is cut-off,” noted the UN humanitarian official.

The news release also underscored that all parties to the conflict are obliged, under International Humanitarian Law, to do everything possible to protect civilians, ensure they have the assistance they need, and limit damage to civilian infrastructure.

“Nothing is more important than protecting civilians – nothing,” stressed Grande