Cyberbullying makes young people more than twice as likely to self harm or attempt suicide, a major new study has shown.

The growth of social media has left many youngsters vulnerable to online bullying, which can include sending threatening, humiliating of intimidating messages or posting hurtful comments or images.

Around one third of young people claim to have been victims, but the new research suggests it can have damaging and deadly consequences.

Researchers at the Universities of Oxford, Swansea and Birmingham reviewed previous studies on cyberbullying which involved more than 150,000 under-25s across 30 countries over a 21-year period.

They found that cyberbullying raised the risk of self-harm or suicidal behaviour 2.3 times.

Professor Ann John, of Swansea University Medical School, who led the study, said: “Prevention of cyberbullying should be included in school anti-bullying policies, alongside broader concepts such as digital citizenship, online peer support for victims, how an electronic bystander might appropriately intervene; and more specific interventions such as how to contact mobile phone companies and internet service providers to block, educate, or identify users

“Suicide prevention and intervention is essential within any comprehensive anti-bullying programme and should incorporate a whole-school approach to include awareness raising and training for staff and pupils”.