Parents warned 'four in ten children are victims of online cyberbullies'
Trouble: Social networking sites are being used to bully children
Four out of ten children claim to have been targeted by online bullies.
And almost one in five admits to persecuting other youngsters via a home computer.
A study by the online security experts Garlik illustrates the burgeoning problem of cyberbullying.
It found 18 per cent of youngsters freely admit to being online bullies, posting deliberately offensive comments about others and in extreme cases 'stealing' their identities.
While the majority of parents are in the dark about their bad behaviour, a quarter of the young online bullies claim that their parents know about their actions and think they are harmless fun.
Researchers questioned 1,000 children aged between eight and 15, and 1,000 parents across the UK.
Tom Ilube, chief executive of Garlik, said: 'Parents need to track closely their children's online activities to ensure they are acting responsibly.'
John Carr, an expert on child safety on the internet said: 'As the school holidays approach, this research is a timely reminder of the importance of parents and teachers engaging with children, to remind them how serious the consequences of bullying can be.'
