By Tom Miles
GENEVA (Reuters) - An expected Iraqi assault on the Islamic State stronghold of Mosul is likely to cause mass civilian casualties and force hundreds of thousands to flee their homes, the United Nations said on Monday.
It appealed for funds to deal with the humanitarian crisis, saying it would cost $284 million to prepare the necessary aid and up to $1.8 billion to deal with the aftermath.
"The impact of the Mosul military campaign on civilians will be devastating," the U.N. said in the summary of its Iraq humanitarian response plan.
"Mass casualties among civilians are likely and families trying to flee areas controlled by ISIL (Islamic State) are expected to be at extreme risk," it said.
Large-scale displacement of people was expected when Mosul city itself came under attack, it said. Between 1.2 million and 1.5 million people are estimated to live in the city.
"In a worst case, all or the majority of these people will require life-saving assistance and protection," it said.
Difficulties will include operating close to the Syrian border and the need to support civilians who escape across the frontline, transport them hundreds of kilometres to safety, and house and protect them in hundreds of camps, transit centres and reception sites.
In the best case scenario, 300,000 people will be displaced for three months, requiring an aid budget of $143 million. The worst case would be 1 million displaced for a year, meaning a $1.8 billion cost.
In any case, aid agencies need two and a half months of lead time and $284 million before the assault on Mosul starts. If funding comes too late, they will be unable to respond appropriately, the U.N. document said.
Lise Grande, the U.N. humanitarian coordinator for Iraq, told Reuters last month that at least 430,000 more people could be displaced this year in Anbar, Iraq's desert province stretching west from Falluja to the Syrian border.
The United Nations asked for $861 million in January this year for Iraq, the minimum needed to keep people alive, knowing that it was unlikely to get the $4.5 billion needed to offer 10 million Iraqis international standards of care, the document said.
However, less than 40 percent of that appeal has been received, stopping 99 frontline aid programmes and hindering assistance for 85,000 people who have fled from Falluja.
(Reporting by Tom Miles; Editing by Angus MacSwan)