Children as young as eight are more likely to fall prey to cyber bullies and online predators, as they are flouting Facebook website age restrictions, police and teachers have warned.

Peer group pressure is forcing increasing numbers of primary school-aged children to sign up to the popular social media site without the knowledge of their parents.

Childhood experts said these children have to lie about their age because users have to be over 13 to create a Facebook account.

Internet safety advocate Robyn Treyvaud said, when she asks a class of year four students if they are on Facebook, most put up their hands.

Treyvaud, who advises schools on cyber safety, said the children are naive about the impact of sharing personal information online and are influenced by hearing older children talking about Facebook.

“Kids who are 10 don’t want to be 10 online. They want to be the cool 18-year-old and the reality is they can be,” the Sydney Morning Herald quoted Treyvaud as saying.

“We make assumptions that because the kids are tech-savvy and know how to sign up to Facebook accounts without mum and dad knowing about it, they can do all the navigation of the technology, but they are not equipped to navigate the sorts of negative experiences they have when they go online.”

“Evidence shows the greatest harm comes from their peer group, not the dodgy online stranger or predator,” said Treyvaud.

The international Norton Online Living report found that 62 per cent of children aged eight to 17 have had a negative experience online, such as accessing inappropriate content, cyber bullying, giving out personal information and importing computer viruses.

Senior Constable Michael Steele told The Newcastle Herald a 10-year-old boy told him he had been chatting online with a man in Queensland. He said children “do not really understand there are paedophiles . . . trawling cyberspace”.

Mosman Public School principal Kate Cooper has warned parents in her newsletter about children signing up for Facebook. Cooper wrote that some parents were “unaware that children must be over 13 years of age to sign up . . . Whilst this is not strictly a school matter, we are very concerned about internet safety”.

Child psychologist Michael Carr-Gregg said children using social media were “one of the great unaddressed public health issues of our time”.

“Parents will spend a fortune teaching their children to swim or drive but not any energy, money or emotional effort to teach their kids to stay safe online,” she added.