Children as young as 12 are carrying out "shocking" sexual violence against other children, according to an official report published on Tuesday.

The Office for the Children's Commissioner for England warned that rape was considered "normal and inevitable" in some areas, particularly among gangs.

Deputy Children's Commissioner Sue Berelowitz highlighted the "sheer levels of sadism" uncovered by the two-year inquiry into child exploitation and gangs.

"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.

"This is a deep malaise within society from which we must not shirk," she said.

The report found that 2,409 youngsters were known to be victims of child sexual exploitation by gangs and groups while a further 16,500 were deemed to be at risk.

The problem exists in every area of England and is not just confined to deprived, inner city areas, according to the report.

"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," added Berelowitz.

Research by Bedfordshire University into sexual violence in gangs suggested that two thirds of young people know of young women who have been pressurised or coerced into sexual activity.

Half of those questioned cited examples of young people offering sex in return for status or protection, while two fifths said they knew of individual cases of rape and over a third gave examples of gang rape.

Another study by London Metropolitan University suggested that young people had confused views of the meaning of "consent", with many believing that sex without consent is not rape if those involved know each other.

"The victim, usually a girl (but boys are victims too) is invariably blamed for their own assault", the study said.

"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."

The report said the problems remained "almost entirely invisible" to many professionals working in child care and child protection.