Online bullying is growing at an exponential rate because of a lack of high-profile action to tackle the problem, the head of an anti-bullying charity said.
Liz Carnell, the director of Bullying Online, said prompt police action had helped curb the "happy slapping" craze 18 months ago, but bullies had now moved on to harassing people through social internet sites like Bebo, Piczo, YouTube and MySpace.
"We're seeing far more cases of this happening than six or even three months ago," she said.
"After a series of high-profile prosecutions, happy slapping seemed to die out.
"But then people's memories fade, and they started doing it again."
Ms Carnell said schools and the police needed to get involved more to try to stamp out online bullying.
She added: "Online bullying is a huge problem because it's not like normal bullying. When you have bullying on the internet, it's very humiliating because everyone can see it. It's not just a personal insult.
"It can start with a few insults and then people join in and before you know it, a child is the subject of a hate campaign."
Chris Cloke, the head of child protection awareness at the NSPCC, said: "Twenty four hour internet access and an increased use of mobile phones means that cyberbullying is on the rise and young people can be abused by text or email.
"It is vital that schools ensure they have policies in place to prevent and tackle it and parents need to understand how their children can use new technologies safely to protect themselves at all times.
"Bullying in cyberspace must be tackled with the same vigilance as any other form of bullying."
In the last recorded year, there were 37,074 calls to Childline about bullying from schoolchildren.