MySpace has reported purging 90,000 sex offenders, but Robert Hart, chief executive of Intuitive Media, said the fact that it took it two years to purge known names of sexual offenders listed in the public domain is outrageous.
"More worrying is that those websites can simply not protect against the offenders that have not yet been caught trying to sexually solicit children," he said.
MySpace claims it is doing everything it can to keep sex offenders off the site. The company said it uses a "best-of-breed solution" that is continually updated to deal with an ever-changing environment.
According to Hart, when there is a mix of children and adults on a networking website it is almost impossible to police their interaction, particularly when most sites cannot authenticate the age of users.
Without foolproof identity and age verification and various well thought out mediation tools, social networks are not safe for children, said Hart.
He acknowledges that social networking service providers have an important role to play in keeping children safe, but said parents need to be aware of what their children are doing online and children need to be taught safe internet behaviour.
This week, authorities in the US state of Texas announced the 30th arrest of a sex offender accused of using MySpace in violation of his parole by the state's cybercrime units.
The latest arrest coincides with MySpace handing over the names of the 90,000 registered sex offenders found on its site to the Connecticut Attorney General's office to comply with a court order.
Four others have been arrested on suspicion of using the social-networking site to meet and sexually proposition undercover agents posing as minors under the age of 15, the Texas Attorney General's office said in a statement.
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Risk management blog: MySpace, fake profiles, and Internet surveillance