An education authority is warning parents about an internet chatroom being used for "unsavoury activities".
A council blocks access to a teen website after 'danger' claim
Norfolk County Council said it had told county heads the bebo.com site was "inappropriate" and many schools had already blocked computer access to it.
An e-mail sent to all school heads in Norfolk said the site was being used for "bullying and pornography".
Schools were advised in an e-mail to warn parents about their children using the site which they felt posed dangers.
Norfolk is thought to be the first education authority to issue such a warning about the site but schools in other parts of the country had already expressed concerns.
Danger at home
"This website cannot be accessed on school computers because it has been blocked," said a council spokesman.
"Our concern is that children will access it at home and we have advised head teachers of those concerns."
The e-mail sent to schools said: "It would appear that the website is being used for bullying, pornography, drugs references and other unsavoury activities.
"Whilst the website is blocked from access on the Norfolk schools network we are obviously powerless to dictate what is viewed in the home.
"We would therefore like to advise schools that they make parents aware of this site and the dangers associated with it."
Bebo said on Monday there had been fear and overreaction but it was important for parents and schools to get involved in the site.
Founder Michael Birch said: "We've taken safety very seriously right from the start as users can access each other's details.
"We are taking an active role in educating users about online safety so we include security tips on every page."