The number of children accused of carrying out sexual offences at UK schools has almost trebled in four years, according to a new study.
Figures compiled by children's charity Plan International UK show the number of sex crimes reported rose from 719 in 2011-12 to 1,955 in 2014-15.
In total some 4,643 sexual offences were reported at UK schools between 2011 and 2015.
The investigations also found the number of allegations of sexual crimes reported at schools averaged 10 each school day.
The data was obtained by the charity through Freedom of Information requests from 34 out of the 45 police forces in England, Wales and Northern Ireland, however Police Scotland declined the request on cost grounds.
The figures relate to sexual assaults where the location was recorded as a school.
In England, boys and girls as young as five were accused of carrying out sexual offences, while the youngest alleged victims were also aged five.
In one case, a five-year-old girl was reported to police for sexually assaulting a boy under 13.
In Wales, the youngest alleged victim of a sexual offence was just four. No details of the allegation or the child's gender were given.
Welsh police also investigated claims a five-year-old boy had sexual activity with a five-year-old girl.
The study also showed nearly two thirds (66%) of the alleged victims are female, and 94% of the alleged offences are committed by males.
Plan International UK said the findings are "alarming" and demanded that the UK Government make relationship education compulsory.
Lucy Russell, the girls' rights campaign manager for the UK charity, told the Press Association: "We are very concerned about these findings.
"Sadly we are not really shocked because we have heard time and time again from girls in the UK that sexual harassment and sexual violence in schools is sadly quite commonplace.
"It is something they are really worried about."
A spokesperson for the NSPCC in the UK said: "The rise in reporting to police reflects a very worrying trend which should make all authorities and parents sit up and take notice and then redouble their efforts to keep children safe from sexual abuse, both inside and outside of school."