FANTASY has always been important for the developing mind - whether it be playing doctors and nurses at infant school or dreaming up an exciting story for English GCSE.

Now those vivid juvenile imaginations have discovered a new outlet: Internet chatrooms.

Here, teenagers experiment with different identities and try them out on the people they meet. They may disappear into a sideroom for a private conversation and order more drinks from the bartender if they want to impress.

In the real world, their parents may be careful about who they meet, and when and where. In cyberspace they can be out partying all night and talking to whoever they like - all without leaving the comfort of their own bedrooms.

Take Sara and Susie for instance. By day they are two normal 14 and 16-year old schoolgirls with the usual gamut of favourite pop bands, fashions and television programmes.

In the evening they become Sexy Sadie and Winsome Wendy, claim to be 16 and 18, and team up with their chatroom friends.

“The fun is that you can be anyone you want to because everyone lies,” says Sara. “Basically you are meeting interesting people - people you wouldn’t normally meet - but you have no idea who they really are.”

Sara and Susie are not alone, of course. Most of their friends are hooked on chatrooms too. They know that rule number one of “Netiquette” is never to give away your true identity. They also steer clear of the on-line nutters and those looking for cybersex.

“They would spend every night on it,” said Sara’s mother, who tries to limit chatroom visits to half an hour. “They think it is just a joke. My concern is that anyone could be on the other end and hey have no idea what they are letting themselves in for.”

Tony Blair’s recent promise to increase Internet access for all has raised concerns that, without strict policing, more paedophiles could target chatrooms and more youngsters could be lured into arranging meetings with their new “friends”.

That worry became a reality for two families in Cumbria last week when their 15-year-old daughters disappeared from home to meet up with chatroom friends in Manchester. They turned up four days laterunharmed.

Julian Sefton-Green, a research associate at the London University institute of education’s new centre for the study of children, youth and media, believes schools should be teaching safe cyber behaviour.

“We already teach children safe and sensible ways to conduct themselves - it shouldn’t matter whether it’s on the street or on-line,” he said.

As long as children avoid giving out real names, addresses, telephone numbers or pictures of themselves, chatrooms should be seen as harmless.

“These chatrooms are all steamy places in the best adolescent traditions,” said Sefton-Green. “Experimenting with different identities is part and parcel of growing up. Chatrooms allow children the freedom to do that in a safe manner.”

Guidelines for safer surfing: Netiquette

Don’t reveal your address, telephone number, school name, send a picture or arrange to meet anyone you know through the internet

Don’t provide credit card or bank details without first checking with a parent or carer

Keep your password secret or people could pretend to be you

Remember, people don’t always tell the truth on-line

If someone says or writes something in a chat room or e-mail that makes you uncomfortable, report it

Never respond to nasty or suggestive messages.