More than one million people, including hundreds of thousands of children, are facing an "impossible decision" as a huge military assault is launched in Iraq against Islamic State fighters.
Coalition forces are backing local government and Kurdish military with air strikes in an attempt to wrest Mosul, the country's second-largest city, from the control of Isis.
Charity Save the Children warned that safe escape routes out of the city for civilians caught up in the conflict "do not exist". In particular, there are hundreds of thousands of children who face further trauma amid the bombardment of the city.
Spokesman Ruairidh Villar has advised the families and children to stay inside and erect a white flag on top of their homes in a bid to stay safe.
Speaking from Irbil in Iraqi Kurdistan, he told the Press Association: "Whether families and children stay or they flee, right now it's an impossible decision.
"We are calling on the UK Government to put pressure on the Iraqi and coalition forces around Mosul now to establish safe corridors, safe escape routes for children to get out.
"These children have been through two years of [Isis] rule, subject to an education which is focused on extremist violence. Some children have not gone to school at all.
"There's been a lack of food and medicine and after all that they're going to have to escape from what looks to be a very bloody conflict indeed."