The Government is not doing enough to prevent children being trafficked into Britain, international children's group Unicef said.
Youngsters from Albania, Moldova, Romania and Kosovo are being smuggled to be used in the sex trade, slavery or for begging.
The report - Action to Prevent Child Trafficking in South Eastern Europe - said the problem could only be tackled by addressing the root causes and the pattern of supply and demand.
Report author Mike Dottridge said that awareness-raising campaigns were "unfocused".
For example, some carry stereotypical images of men lurking in the shadows, when in reality traffickers are often families or friends.
Others target adults rather than the children who need to know how to protect themselves and where to go for help, he said.
Children need education to provide them with the means to protect themselves, the report urged.
Agencies such as the police, immigration officials and social services should also be better trained to help identify child trafficking, it added.
Graham Maxwell, programme director of the UK Human Trafficking Centre, which opens in October, said a 15-year-old girl was worth £8,000 to the gangs.
Mr Maxwell, who is also deputy chief constable of South Yorkshire Police, said the new centre would aim to look at the co-ordination of welfare arrangements for victims, as well as increasing awareness of people in the public sector of the scale of the problem.
