The government has announced new measures to crack down on bullies who use technology to target pupils and teachers.
In guidance published on Friday, ministers advised schools to involve the police to help tackle the most serious cases of 'cyberbullying'.
The news comes after a study from the Department for Children, Schools and Families found that more than a third of 12- to-15 year-olds had been bullied by people using mobile phones and the internet.
Ministers developed the advice following consultations with anti-bullying experts and social networking websites including MySpace and Bebo.
There will be an online campaign launched on these websites and schools will be given a film to screen during lessons.
Teachers will be advised on how to draw up policies to prevent cyberbullying, and pupils will be given practical tips on how to act if they become victims.
Schools secretary Ed Balls said: "The vast majority of schools are safe environments to learn in.
"However, we know that behaviour, particularly bullying, is a key concern for parents and bullying of any kind is unacceptable.
"Cyber-bullying is a particularly insidious type of bullying as it can follow young people wherever they go and the anonymity that it seemingly affords to the perpetrator can make it even more stressful for the victim.
"Cyber-bullying takes different forms - threats, intimidation, harassment or 'cyber-stalking', unauthorised publication of private information or images, impersonation and 'happy slapping'."
The move received a warm welcome from teaching unions, who say it will help prevent bullying at school.
Mary Bousted, the general secretary of the Association of Teachers and Lecturers, said almost one in five of her members had complained of cyberbullying and called for more support for staff.
"All schools and colleges should have policies to protect their teachers and support staff from cyber-bullying, and should make a commitment to fully support anyone who is a victim," she said.
The NASUWT union has been calling for pupils' mobile phones to be banned during school and seen as potentially offensive weapons.
Its general secretary Chris Keates said: "Teachers will be particularly pleased that the secretary of state has recognised that the focus on pupils being cyber-bullied should be matched with equal concern about the increasing numbers of teachers who have become victims of vicious and debilitating abuse."

Dods Parliamentary Communications Ltd