Criminal gangs are targeting girls as young as 12 in schools and forcing them into prostitution, according to research by a charity that works with sexually exploited young people.
The girls are often approached by boys of a similar age then "groomed" - flattered, given presents, and offered drugs and alcohol - before being abused by older men, it says.
The Coalition for the Removal of Pimps (Crop), has worked with more than 140 families over the past 11 years whose children have been abused through prostitution.
Hilary Willmer, its chair, said: "This can happen to absolutely any family.
Boys are often used to make initial contact with the girls, in and outside schools, in shopping centres or arcades. They befriend the girls, who may be as young as 12.
"After some time, the girls are introduced to older teenagers or men in their twenties who take them out in their cars, buy them mobile phones, meals and so on. The girls, who are inexperienced and naive, think they have an exciting new boyfriend. Then it becomes more sinister. They are taken to other, normally much older, men who say it's payback time for the presents. They are abused, in effect raped."
She said it was difficult to identify when a girl is being groomed, particularly in the early stages. Warning signs, however, can include mood changes, aggressive or violent behaviour, truanting, and new possessions, such as jewellery and mobile phones.
The Leeds-based charity spoke to 106 families whose children have been abused through prostitution between June 2002 and June 2005 and conducted in-depth interviews with 10, mainly in Yorkshire.
Its report says much of the abuse is carried out by sophisticated gangs and is followed by threats and violence against the girl and her family, who are often too frightened to tell the police or testify in court. One mother said: "I remember my daughter's words, 'Mum, he has brainwashed me so that I cannot leave him ever: I am like his possession'.
"They are taken in, brainwashed and turned against normality. Time and time again she went back to him. It is the grooming and the sweet talk, at which they are good. They promise that bad things and abuse will not happen again, which is not true."
The report identifies Rotherham as a problem area. A pupil at one of two schools which merged earlier this year to form Winterhill secondary was abused through prostitution. "It was broken up and dealt with by the police," said Roger Burman, head of Winterhill. "This was more than five years ago, before I came to the school. It's not a problem now."
He said it was vital that schools had a strong pastoral system. "You have to create an atmosphere where girls or someone on their behalf feel able to talk about problems like child prostitution."
But Crop, founded in 1996 by Irene Ivison whose daughter was forced into prostitution and murdered at the age of 17, says schools are often unable to respond. The report said this was "primarily because they lack knowledge about pimping networks, but also because they are concerned about their reputations. School authorities may not want to acknowledge the problem, which may result in parental concerns being ignored."
This view, however, is challenged by Mr Burman. "I can see people not wanting to broadcast it but I don't think that anyone would not deal with the problem because they were concerned about a school's reputation," he said.
Ginny Wilkinson, of children's charity Barnardo's, said it was important for teachers to work with agencies such as social, health and youth services to tackle child prostitution. "Parents and all adults have a responsibility to report their concerns to any professional working with children," she said.
The report Parents, Children and Pimps: Families speak out about sexual exploitation is available from CROP (tel) 0113 240 3040