The same group of US attorneys-general who have managed to get MySpace to block about 29 000 registered sex offenders from its pages is now turning its attention to Facebook, where three sex offenders have so far been identified. 

Unlike MySpace where users are protected by pseudonyms, Facebook has a number of privacy features in place and encourages members to share personal details.
It also has checks and balances in place to protect members under the age of 18 from being contacted by adults not affiliated to a school.
Facebook, originally developed as a sharing site for Harvard students, now boasts about 33-million mainstream users.
There are about 600 000 registered sex offenders in the US.