In the past year, 24 police forces across the UK have arrested children under 13 on suspicion of rape and seven detained at least one 10-year-old.
The figures were said reflect the disturbing impact that online pornography is having on the young children who are accessing it.
The NSPCC said there was "undoubtedly" a link between children perpetrating sexual assaults and easy access to online pornography.
The porn is giving them "a distorted picture of what sexual relationships should be about," a spokesman said, warning that it was exercising a powerful influence on youngsters today.
"Some young people do not have an understanding of consent," he said. "If they want something they will go out to get it, whatever the consequences.
"There is a definite link between this and watching hardcore porn. It is an issue of entitlement.
"If a child has watched a rape scene the same child might attempt to act that piece of behaviour out.
"The children talk about acting out what they have watched."
John Carr, from the Children's Charities' Coalition on Internet Safety, added: 'There is already a widespread feeling that the internet is playing an unhealthy part in the early sexualisation of children and these revelations about the arrests of ten year olds for rape will add fuel to the flames."
The figures, obtained through a Freedom of Information request by the Daily Mail, showed that 31 police forces arrested children aged 10 to 13 on suspicion of rape in the past year.
In seven regions, the youngest child arrested for rape was aged just 10, while six forces said the youngest child suspect they had arrested was aged 11, and 11 forces said the youngest was 12.
Some 357 children aged 18 and under were convicted of sex crimes including rape, sexual assaults on other children, grooming, incest and taking or possessing indecent images of minors.
A 10-year-old boy in Merseyside was reportedly involved in the suspected gang rape of a 12-year-old girl in a park, while Avon and Somerset Constabulary arrested a 10-year-old accused of forcing a friend to perform a sex act on several occasions.
Police in Essex, Derbyshire, Durham, Gwent, and Strathclyde also detained children aged 10 on suspicion of rape last year.
A child abuse investigator working for a South East England police force said: "When we arrest juveniles for sex crimes we increasingly find they have accessed hardcore pornography.
"This is often on their phones where they store videos and pictures to share with their friends. It is not something my colleagues would have dealt with ten years ago."
