Parents are to get safety advice on networking websites such as MySpace to protect children from paedophiles who could use the sites to "groom" victims.
Bebo groups users by school and college
The Child Exploitation and Online Protection Centre (Ceop) will run a series of workshops in UK for parents, children and teachers.
Ceop said it was concerned that children were posting personal details on so-called community sites.
The body said one in 12 children met up with someone encountered first online.
In the UK, social sites such as Bebo and MySpace have become extremely popular in recent years with each website receiving more than two million visitors every month.
Other sites include Friendster, Facebook, Orkut and MSN Spaces.
Jim Gamble, chief executive of the Ceop Centre, told BBC News that the organisation would be talking to parents, children and the industry to ensure the sites were as safe as possible.
He said: "Children need to understand the internet has opportunities but with that come negatives.
"Do not share information online that you would not share offline. Do not meet someone offline that you met online."
He said Ceop wanted to instil in children and young people a sense of social responsibility when it came to using community sites.
"We will be using the workshops to listen to children to find out how they want to occupy these places safely," he added.
Sites such as MySpace let users leave details about their lives online and encourage people to "network" with other users.
A typical page will feature a user's interests, a list of their favourite music and films, a photo gallery, video clips and a blog.
Bebo's users can also talk to each over a webcam and one newspaper in the UK printed extracts of a conversation in which a young person was encouraged to strip in front of the camera by an anonymous user.
54% of Bebo UK users are under 18
31% of MySpace UK users are under 18
MySpace was bought for £308m by News Corp
MySpace and Bebo are the fifth and sixth biggest brands online in terms of audience size
Bebo is opening a London office after an £8m investment
Source: Nielsen NetRatings
Matt Colebourne, chief executive of youth community site Lunarstorm UK, said his company used computer systems, dedicated security staff and volunteers on the site to watch out for inappropriate behaviour.
He said social networks were popular "because the digital generation has part of its personality online".
He has invited the industry to set up a safety standards group called the Online Community Special Interest Group (Oncomm).
"The industry has got to decide if it wants to serve adults or children," he said.
Online communities should not be mixing content that is seen by both adults and children, he warned.
In its safety tips section, MySpace reminds users that their profiles are public and says not to post information "you wouldn't want the world to know".
It also warns that "people aren't always who they say they are".
Bebo tells users they can choose to let only their personal friends see their profile.
The dangers have been highlighted by the head teacher of a Kent girl's school who wrote to parents after realising that 700 of her students had signed up to a networking site.
She considered that some of the images that had been uploaded by the pupils were indecent and could be a lure for paedophiles.
Linda Wybar, head teacher of Tunbridge Wells girls' grammar, also banned the site from her school.
More than half of Bebo's UK audience are under 18 years old, compared with a third of MySpace's users, according to latest net figures.
No-one from Bebo or MySpace was immediately available for comment.