An alarming 75% of all rape and sexual assault victims seen by experts are under 18 – and 66 of the 220 victims are younger than 11.

The figures from the Sexual Assault Forensic Examination (SAFE) Centre show a huge increase on the previous 12 months, when 46% involved youngsters under 18.

The rise is partly due to young teenagers being exploited into having sex by older boys or men.

Today, police described the situation as a "tragedy" for the mainly female victims – some of whom end up forced into prostitution.

Det Insp Steve Hobson said: "The methods employed are as diverse as the offenders and include pseudo online identities to the more traditional forms of grooming such as buying victims presents and making them dependent on drugs and alcohol.

"The tragedy of these situations is the victims frequently fail to recognise the extent to which they are being exploited and therefore place themselves at greater risk.

"Many victims find themselves being coerced into having sex with multiple partners or being forced into the sex trade."

Around one in five rape and sexual assault cases seen by the flagship SAFE centre, based at the Royal Preston Hospital, from April 2007 to April 2008, were "looked after" children in foster or Local Authority care.

One victim was Felicity, a normal, happy, teenaged girl living at home in Lancashire until she got lured into a sexually exploitative relationship at the age of 14.

She was groomed by an older man who became her "boyfriend," luring her with presents as well as alcohol and drugs. She played truant from school, and attended adult parties – before being passed around a network of predators for sex.

Her mother described the change in her daughter. She said: "It was as if there was someone inside her controlling her and telling her what to do and encouraging her to lie, steal and truant."

Another victim was 13-year-old Jennifer. A bright and popular girl with many friends, her route to school regularly took her past the address of a 39-year old man, James. Using alcohol, cigarettes and other gifts, he befriended her – and eventually became her "boyfriend."

Jennifer became secretive, told lies and took time off school, having both unprotected consensual and non-consensual sex with him.

It was at this point that the Child Sexual Exploitation team at Lancashire Police intervened and identified the problem through Jennifer's school. Officers arrested James on suspicion of child abduction and he was later jailed.

Specialist workers believe sex exploitation is becoming a real problem – with these cases being the tip of the iceberg.

Tina Woods, child and young person advocate at the SAFE Centre, said: "This is a particularly vulnerable age group. Predators target younger women and men such as those in care. Sexual exploitation is on the rise and these figures prove that."

DI Hobson added: " Over the last three months a team of officers from Preston have been targeting offences committed against vulnerable young people by older predatory offenders.

"While this team is still in its infancy it has already dealt with in excess of a dozen referrals. The children involved are all female and range in age from 14 to 17.

"The offenders range from early 20s to late 60s and are from a number of ethnic and social backgrounds."

All names in case studies have been changed.

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