'Elizabeth' was raped by 10 UN peacekeepers in Ivory Coast
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.
After research in Ivory Coast, southern Sudan and Haiti, the charity proposed an international watchdog be set up.
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 victims are suffering sexual exploitation and abuse in silence
Heather Kerr Save the Children
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.
A 13-year-old girl, "Elizabeth" described to the BBC how 10 UN peacekeepers gang-raped her in a field near her Ivory Coast home.
'Elizabeth' tells the BBC about her abuse
"They grabbed me and threw me to the ground and they forced themselves on me... I tried to escape but there were 10 of them and I could do nothing," she said.
"I was terrified. Then they just left me there bleeding."
No action has been taken against the soldiers.
The report also found that aid workers have been sexually abusing boys and girls.
"In recent years, some important commitments have been made by the UN, the wider international community and by humanitarian and aid agencies to act on this problem," said Save the Children UK chief executive Jasmine Whitbread.
"However, all humanitarian and peacekeeping agencies working in emergency situations, including Save the Children UK, must own up to the fact that they are vulnerable to this problem and tackle it head on."
UN SEXUAL ABUSE SCANDALS
2003 - Nepalese troops accused of sexual abuse while serving in DR Congo. Six are later jailed
2004 - Two UN peacekeepers repatriated after being accused of abuse in Burundi
2005 - UN troops accused of rape and sexual abuse in Sudan
2006 - UN personnel accused of rape and exploitation on missions in Haiti and Liberia
2007 - UN launches probe into sexual abuse claims in Ivory Coast
After research involving hundreds of children from Ivory Coast, southern Sudan and Haiti, the charity said better reporting mechanisms needed to be introduced to deal with what it called "endemic failures" in responding to reported cases of abuse.
It also said efforts should be made to strengthen worldwide child protection systems.
Heather Kerr, Save the Children's Ivory Coast country director, says little is being done to support the victims.
"It's a minority of people but they are using their power to sexually exploit children and children that don't have the voice to report about this.
"They are suffering sexual exploitation and abuse in silence."
Save the Children says the international community has promised a policy of zero-tolerance to child sexual abuse, but that this is not being followed up by action on the ground.
A UN spokesman, Nick Birnback, said that it was impossible to ensure "zero incidents" within an organisation that has up to 200,000 personnel serving around the world.
"What we can do is get across a message of zero tolerance, which for us means zero complacency when credible allegations are raised and zero impunity when we find that there has been malfeasance that's occurred," he told the BBC.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.