The number of reported child sex offences has risen by a third to the equivalent of more than 113 per day, a leading children's charity has said.
Police in England and Wales recorded a total of 41,457 sexual offences against under-18s in the financial year 2014/15 - up from 31,238 the previous year, a 33% rise.
Including Scotland and Northern Ireland, the total for 2014/15 rises to 45,456, the equivalent of more than 124 per day, or more than five per hour.
Among the crimes where the gender of the victim was recorded, 30,393 were female and 7,639 were male.
NSPCC chief executive Peter Wanless said: "This dramatic rise is deeply worrying and shows just how extensive this appalling crime has become, claiming many victims every day, every hour.
"Sexual abuse can shatter a child's mental health. It can leave them anxious, depressed and even suicidal. That is why it is crucial every single child who has endured abuse and needs support must get timely, thorough help so they can learn how to handle disturbing emotions and behaviours and rebuild their lives."
Among the forces in England and Wales that were able to give an age breakdown for the figures, a total of 10,757 were aged 10 and under, including 2,409 who were under four.
The charity said a number of factors could be behind the rise, including changes in the way police record crime, survivors being encouraged to speak out following high profile abuse cases, and the "major problem" of online grooming.
A spokesman said: "Sex offenders grooming children online is a huge problem, and children in the UK can be targeted from anywhere in the world.
"Online predators may trawl social networks, online game environments and other areas popular with children to build trust with young people and exploit any vulnerabilities they discover.
"The methods are sometimes very sophisticated, or they may take a more scattergun approach and target hundreds of children at a time."
The charity has launched a campaign called It's Time, urging the Government to increase funding and to ring-fence money for support services for children who have been abused.
The National Police Chiefs' Council lead for child protection, Chief Constable Simon Bailey, said: "The figures collated by the NSPCC on child sexual offences reported to police are another reminder of the shocking scale of child sexual abuse.
"Changes in police recording and victims' improved confidence in how the police will deal with abuse have played a significant part in the increase in reports to us. But am I now starting work with academics to consider whether more children are actually being abused.
"The internet has opened up new opportunities for abusers to groom children, view indecent images and watch and direct live sexual abuse of children, and we need to understand the impact of this.
"Police have improved our response to sexual abuse and every single day we are safeguarding children at risk, investigating offences and bringing abusers to court.
"However by the time the report comes to us, the damage is done, so colleagues working in social care, education and health need to work together to stop abuse before it happens.
"Police work will continue but we ask everyone to help us by being alert to signs of abuse and sharing any concerns however small they may seem."