School and college staff should assume that peer-on-peer abuse is happening even if no reports are made, the Department for Education (DfE) has said.

Updated safeguarding guidance says staff in schools and colleges should reassure victims that they will be taken seriously, and that they will be supported and kept safe when they make a report of abuse.

It comes after Ofsted’s review last month concluded that incidents of sexual harassment and abuse have become “normalised” for schoolchildren.

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The DfE has published strengthened Keeping Children Safe in Education guidance - which will become mandatory in all post-16 settings for the first time - and has updated its advice on how schools and colleges can support young victims of sexual abuse, violence and harassment.

The updated guidance - which will not come into effect until September - explains the risks associated with peer-on-peer online abuse and warns that such abuse can happen outside the school or college, and can be hidden.

It comes after a recent Ofsted report found that children often do not see the point of reporting sexual harassment because it happens so frequently, while many teachers consistently underestimate the scale of these problems.

Inspectors were told that boys are sharing “nudes” among themselves like a “collection game” on online platforms, while some girls have experienced “unwanted touching in school corridors”.

The watchdog visited 32 state and private schools and colleges, and spoke to more than 900 young people about sexual harassment, after thousands of testimonials were posted on a website.

In April, the government asked the schools watchdog to look at safeguarding policies and experiences in schools and colleges following the deluge of anonymous reports made to the website Everyone’s Invited.

The updated DfE guidance also adds a section on dealing with unsubstantiated, unfounded, false or malicious reports, as well as adding information on child criminal exploitation, which makes clear that the experiences of girls being criminally exploited can be very different from that of boys.

Baroness Berridge, minister for the school system, said: “Ofsted’s review of sexual abuse and harassment showed us how prevalent these issues are in young people’s lives, not just at school or college but often outside of school.

“That is why we are updating safeguarding guidance to make it absolutely clear that staff should assume that, even if there are no reports of peer-on-peer abuse, it could still be happening - and that where reports are made, they should reassure victims that they will be taken seriously.

“We are also, for the first time, making the guidance mandatory in all post-16 settings.

“We have also clarified the expectations for anyone working in a position of responsibility at schools and colleges to respond appropriately to concerns - from headteachers and teachers, to safeguarding leads and governors - so that pupils attend school every day ready to learn, feeling confident that they will be safe.”