Police are recording a soaring number of alleged sex offences committed by children against other youngsters, an investigation found.
Last year there were 9,290 reports of such cases to forces in England and Wales, a jump of 78% compared to 2013, according to figures obtained by charity Barnardo's.
In total, there were 32,452 reports to police of alleged sexual offences by children on other children over the four year period, an average of more than 20 every day.
The figures relate to instances where the alleged perpetrator and victim are both aged under 18.
Barnardo's said the data, obtained under Freedom of Information rules, show the number of reported cases more than doubled in 12 force areas between 2013 and 2016.
Simon Bailey, National Police Chiefs' Council Lead for Child Protection, said: "We believe we can attribute these increases to more awareness and greater victim confidence.
"We also have to look at the possibility that more abuse is being perpetrated and if technology is facilitating this.
"These figures highlight the importance of building resilience in young people and educating them about sexual relationships.
"This can't be left to chance."
Barnardo's chief executive Javed Khan said the charity warned last year that "unless child on child sexual abuse is dealt with head on, it may become the next scandal in our society".
He added: "These results are another wake up call to the extent of the problem.
"We're deeply concerned more children may be sexually harming other children."
Conservative MP Nusrat Ghani called on the Government to work with schools, local authorities, police and voluntary organisations to tackle the issue.
She added: "In this smartphone age, parents must also play a vigilant role in protecting their children from harmful sexual behaviour and from harmful sexual images that cause damage they are too young to understand."
A Government spokesman said: "Child sexual abuse is a horrendous crime and this Government is committed to preventing children and young people from becoming both victims and perpetrators.
"Our ongoing 'Disrespect NoBody' campaign is helping young people understand what a healthy relationship looks like and to re-think their views on controlling, violent and abusive behaviour."