A crackdown on cyber-bullying is being launched in East Sussex with a new initiative led by the council.
Schools are being issued with advice on how to protect pupils who receive abusive messages on their phones, or are taunted via e-mail or in chatrooms.
According to the children's charity NCH, one in five children have admitted to being bullied through their mobile phones or online.
Councillor Rupert Simmons said tackling bullying in all forms was a priority.
He said East Sussex County Council was one of the first local authorities in the UK to introduce guidance on cyber-bullying.
"In some ways, cyber-bullying is even more invasive for young people as the bullying follows them wherever they go and is not confined to school premises," he said.
"It's important to make young people, staff and parents aware of the dangers and ways to reduce the risk, as well as provide an environment where bullying can be freely reported and discussed."