Children as young as six are being sexually abused by peacekeepers and aid workers, says a leading UK charity.
Children in post-conflict areas are being abused by the very people drafted into such zones to help look after them, says Save the Children.
Save the Children said it had sacked three workers for breaching its codes, and called on others to do the same.
The three men were all dismissed in the past year for having had sex with girls aged 17 - which the charity said was a sackable offence even though not illegal.
The UN has said it welcomes the charity's report, which it will study closely.
Save the Children says the most shocking aspect of child sex abuse is that most of it goes unreported and unpunished, with children too scared to speak out.