Children are committing shocking sexual assaults against each other, "profoundly distressing" evidence suggests.
The scale and nature of this sexual violence - including rape - indicates a "deep malaise" within society that needs to be dealt with, according to a damning report by the Office of the Children's Commissioner for England.
It suggests that while the fact that paedophiles prey on young children is widely recognised by society, the idea of children abusing each other - through gangs or groups - is rarely acknowledged.
But the problem is prevalent in every area of England and not just restricted to deprived, inner city neighbourhoods, it says. In some cases, the victims are as young as 11 years old, while the perpetrators can be just 12 or 13.
The report, which includes evidence from studies on children's understanding of consent and sexual violence within gangs, warns that youngsters across the country are being exploited and that the authorities responsible for their safety are failing to protect them.
In a foreword to the report - the result of a two-year inquiry - deputy children's commissioner Sue Berelowitz said: "The fact that some adults (usually men) rape and abuse children is generally accepted."
"There is, however, a long way to go before the appalling reality of sexual violence and exploitation committed by children and young people is believed."
She adds: "We have found shocking and profoundly distressing evidence of sexual assault, including rape, being carried out by young people against other children and young people."
"While we have published chilling evidence of this violence in gang-associated contexts, we know too that it is more widespread than that. This is a deep malaise within society from which we must not shirk."
Research into sexual violence in gangs, conducted by Bedfordshire University, revealed that two thirds of the young people questioned (65%) knew of young women who had been pressurised or coerced into sexual activity, while half gave examples of youngsters offering sex in return for status or protection.
Two fifths (41%) said they knew of individual cases of rape, while over a third (34%) gave researchers examples of gang rape.
Nearly two fifths (39%) of the young people taking part in the study said they knew of cases of youngsters exchanging sex for drugs, alcohol or to pay off a debt, while almost a third (31%) gave examples of girls being used as bait to attract and "set up" males from rival gangs.
A similar proportion (30%) knew of men having sex with a young woman to "disrespect" rival gang members.
But the study also found that just one in 12 of those interviewed said that young people would be likely to report crimes of sexual abuse. Often, sexual violence was seen as normal and inevitable, with young women facing the blame for being abused.
The second study, by London Metropolitan University into young people's views of consent, suggests that these issues are not just limited to gangs and that for many the lines are blurred.
Sex without consent where those involved know each other is often not seen as rape, it found.
"The victim, usually a girl (but boys are victims too) is invariably blamed for their own assault", the study concluded.
"They should not have gone to visit the boy; should not have worn a tight top; should not have had the drink; have 'done it before' so have no right to say no."
Dr Jenny Pearce of Bedfordshire University said that there was a general mindset that does not think about sexual exploitation between young people.
"When we think about child protection in this country we think of familial abuse within the home, we don't think about vulnerable teenagers - 14, 15 particularly 16 to 18," she said.
Ms Berelowitz said that the "sheer levels of sadism" uncovered by the inquiry had been shocking.
"You can not be surprised and still be shocked at the same time, and in terms of the child-on-child, the peer-on-peer, whether in a gang-involved situation or not, it's the chilling inevitability of it that has been really deeply shocking. It's part of the warp and weft of those young people's lives."
She added: "Don't think that this is just confined to deprived neighbourhoods in inner city areas, child sexual exploitation, in general, our findings are that both gang- involved and group- involved is happening across the piece, all over the country in every type of neighbourhood, rural, urban, deprived, not deprived."
The inquiry found that 2,409 youngsters were known to be victims of child sexual exploitation by gangs and groups, while a further 16,500 were at risk.
The Commissioner's final report puts forward new guidance for those dealing with child sexual exploitation, including police, children's services and health staff.
It presents a series of questions - drawn up with young victims - which force professionals to focus on the child and their needs to make sure they get the help they need.
The Commissioner's final report says that urgent steps must be taken to keep children safe, and that many of the known victims had been "badly let down" by the agencies and services that should have been protecting them.
Councillor David Simmonds, chairman of the Local Government Association's children and young people board, said: "Nothing councils do is more important than keeping children safe and this report will make uncomfortable reading for everyone concerned for the welfare of children."
"Child sexual exploitation is a horrific crime which can destroy lives. It is a complex issue to tackle and can be hugely difficult to track. Councils know that we need to do better but, as this report acknowledges, we cannot do this alone. It is time for everyone - including councils, police, teachers and the NHS - to step up to the plate, learn from those areas that are getting it right and show real leadership in stamping out this awful crime."
Matthew Reed, chief executive of The Children's Society, said: "This report shows that there are particular problems with attitudes towards teenage girls, both from professionals and from their peers."
"The report describes that all too often girls and young women are being dismissed as 'promiscuous' or 'slags', rather than being treated as victims of abuse. It is vital that these attitudes are challenged.
"It also shows the double standards many children and young people have towards girls and young women. We need to get better at teaching children about healthy relationships and consent."