A child was the victim of a sex crime every 20 minutes last year and one in four of the known suspects was also under 18, police figures have shown.
More than 23,000 child sex offences - 64 a day - were recorded by police in England and Wales in 2009/10, up 8% on the previous year and 13% from 2007/08. One in four of the victims were aged 11 or under and more than 1,000 were four or younger, the data from the 43 forces showed.
The NSPCC, which obtained the figures under freedom of information laws, said the rise was a real concern and it was clear that more services were needed to address the harmful sexual behaviour of young people, as well as adult offenders.
Of the 23,390 child sex offences, including rape, incest and gross indecency, recorded last year, more than half (12,088) were aged 12-15, while around one in four were aged five to 11 (5,164) and a similar proportion were aged 16 and 17 (5,022).
One in every 25 child victims (1,028) was aged four or under and the ages of a further 88 child victims were unknown. The figures also showed 2,200 of the 9,636 suspects were aged under 18. Britain's largest force, the Metropolitan Police, recorded the most child sex offences (3,672), followed by West Midlands Police (1,531) and the West Yorkshire force (1,205).
Jon Brown, who leads on child sex abuse for the NSPCC, said: "The rise in recorded sex offences against children is a real concern and we need to find ways to help victims and change the behaviour of young offenders. More than 2,000 suspects in these cases were under 18. It's clear we need more services that address the harmful sexual behaviour of young people, as well as adult offenders. We urge everyone to be vigilant and report any concerns they have about a child."
A Home Office spokeswoman said: "These figures are appalling and we'll continue to work with groups like the NSPCC to protect the most vulnerable people in our society. The child sex offender disclosure scheme was rolled out to all police forces in England and Wales earlier this year. This is not only a major step forward in our ability to protect children from sex offenders but also empowers parents and guardians to understand how best to protect their children.
"There are specialist child abuse investigation teams and specialist rape prosecutors in every area and the Government has commissioned a review into the sexualisation of children which will report soon."
But the Association of Chief Police Officers (Acpo) warned that recorded crime figures were "not a good indicator of the prevalence or trends of child sexual abuse". Assistant Chief Constable Peter Davies, the Acpo lead for child protection and child abuse investigation, said: "We know that much abuse goes unreported, and it is conceivable that some increase in recorded crime may be attributable to victims, particularly those who have suffered historic abuse, having greater confidence to report these matters.
"We have a firm commitment to continuing our work. There is much more to do. It is a priority for every force and we must continue to work both nationally and locally to share best practice and specialist skills. We can't do it alone which is where partnerships with organisations such as the NSPCC are so key but we will use every tool at our disposal to keep children safe from harm."