The Iraqi army dropped tens of thousands of leaflets over Mosul before dawn on Sunday, warning residents that an offensive to recapture their city from Islamic State was in its final stages of preparation, according to a military statement in Baghdad.

 

The leaflets carried several messages, one of them assuring the population that advancing army units and air strikes "will not target civilians" and another telling them to avoid known locations of Islamic State militants.

 

The assault on Mosul, the last city still under control of the ultra-hardline Islamic State in Iraq, could begin this month, according to Iraqi government and military officials.

 

Islamic State fighters are dug in, expected to fight hard and have a history of forcing civilians to stay in harm's way during previous battles to defend territory.

 

Reflecting the authorities' concerns over a mass exodus that would complicate the offensive, the leaflets told residents "to stay at home and not to believe rumors spread by Daesh" to cause panic, referring to Islamic State by its Arabic acronym.

 

With a pre-war population of around 2 million, Mosul is around 4-5 times the size of any other city recaptured so far from the militants, who swept through northern Iraq in 2014 and also hold a swathe of Syria.

 

The U.N. last week said it was bracing for the world's biggest and most complex humanitarian effort in the battle for the city, which could make up to 1 million people homeless and see civilians used as human shields or even gassed.

 

"Keep calm and tell your children that it is only a game or thunder before the rain," a leaflet said. "Women should not scream or shout, to preserve the children's spirit."

 

"If you see an army unit, stay at least 25 meters away and avoid any sudden movements," another said.