Sexual abuse of children by aid workers and peacekeepers is rife and efforts to protect young people are inadequate, said a report published on Tuesday.
The study by charity Save the Children UK said there were significant levels of abuse in emergencies, much of it unreported and unless the silence ended, attempts to stamp out exploitation would "remain fundamentally flawed".
Accusations of sexual abuse by U.N. peacekeepers and aid workers around the world have increased in recent years and the United Nations is investigating claims against its soldiers in hotspots such as Haiti, Liberia, Ivory Coast and the Democratic Republic of Congo.
The report said while the U.N. and some non-governmental organisations were stepping up efforts to address the problem, a global watchdog should be established this year to monitor attempts to tackle abuse and champion effective responses.
Save the Children based its findings on visits last year to Haiti, Southern Sudan and Ivory Coast. It held 38 focus group discussions with 250 children and 90 adults, followed up by in-depth interviews with some and desk-based research.
The study found a huge range of exploitation and abuse: children trading sex for food, forced sex, verbal sexual abuse, child prostitution, child pornography, sexual slavery, sexual assault and child trafficking.
The focus groups identified children as young as six as having been abused, although most were aged 14 to 15.
U.N. peacekeepers were identified as the most likely perpetrators by 20 of the 38 groups, although a total of 23 humanitarian, peacekeeping and security organisations were associated with sexual abuse in the three countries.
