The UK government has launched an initiative to stamp out cyber-bullying in schools.

New measures have been put in place to protect teachers and pupils from abusive or offensive phone calls, emails, text messages or online posts.

The campaign includes a cyber-bullying website, new guidance for schools and a short film to help schools tackle bullies who use the internet or mobile phones.

According to government figures, more than a third of children aged between 12 and 15 have been victims of cyber-bullying.

The move was welcomed by the National Union of Teachers, which said that teachers had also been "belittled" online.

Ed Balls, Secretary of State at the Department of Children, Schools and Families (DCSF), said that the majority of schools are safe environments in which to learn, but that the government is aware that bullying remains a key concern for parents.

"Cyber-bullying is particularly insidious as it can follow young people wherever they go. The anonymity that it seemingly affords to the perpetrator can make it even more stressful for the victim," said Balls.

"Cyber-bullying takes different forms, including threats, intimidation, harassment, cyber-stalking, unauthorised publication of private information or images, impersonation and happy slapping."

Balls explained that bullying often uses prejudices, including sexist, homophobic or racist attacks, or preys on physical or mental disability, cultural or religious background, appearance or socio-economic position.

The DCSF's online advice includes a wake-up call to people who may be adding to the problem of cyber-bullying without realising it.

"Even if you are not a ringleader and targeting someone specifically, you can easily be part of the problem by adding abusive comments to an online message board or sending a photo you've received on your phone to your mates," the website says.

"Even though those who use the web to target and bully others think that they can remain anonymous, this is not the case.

"Even someone using a false name or email address can be traced and banned by social networks and email providers if they are found to be bullying others."