One in five young people has been bullied by mobile phone or via the internet, a study suggests.

A children's charity surveyed 770 youngsters and found 14% of 11- to 19-year-olds had been threatened or harassed using text messages.

Bullies had used images taken with mobile phone cameras to intimidate or embarrass one in 10 young people. This included picking on overweight or spotty youngsters and recording and sharing videos of playground violence.

The findings follow reports of so-called "happy slapping" attacks - where assaults on children and adults are recorded on mobile phones and sent via video messaging.

'Intimidated'

The charity said: "For a child or teenager being bullied by mobile phone, it can be terrifying and feel like there is no escape."

"This new research reveals the massive scale of mobile bullying and shows how camera phones are being used by bullies to frighten and intimidate their victims."

Some 26% of digital bullying victims did not know who their tormentor was, the survey found.

"This extremely worrying phenomenon highlights the urgent need to tackle mobile bullying before it ruins more lives."

More than one in 10 of the 770 youngsters, carried out jointly with Tesco Mobile, said they had bullied others via text message, with half of all incidents happening within schools.

But the real problem was bullying, not technology.

The report found that 5% of young people had been bullied in internet chatrooms and 4% via e-mail. And the charity has launched an interactive website - www.stoptextbully.com - to give advice and support.

Anti-bullying charity Bullying Online was warning of text message bullying more than five years ago. The Department for Education warned that children who used mobile phone text messages to intimidate other children could be expelled from school.

Related websites: www.stoptextbully.com