Google has launched a new 3D world platform designed to be safe for teenagers to use.

The Lively platform allows users to design and operate small 3D rooms which can be embedded into blogs and websites.

Unlike Second Life, which is adult-only and boasts a bustling adult economy, Google promised that Lively will not allow explicit content.

The service is open to users as young as 13 and has strict controls on issues such as bullying and harassment.

By Wednesday afternoon, however, the service appeared to be a bit more 'lively' than Google had anticipated. Two of the five most occupied 'rooms' on the service solicited 'sex' in their titles and descriptions.

One room boasted as many as 3,724 occupants. Other rooms could be found advertising such themes as 'cyber sex' and 'hot college girls'.

Google did not return a request for comment at the time of publication.

Pornography worries aside, the search giant hopes that the site will combine the social networking features of its embedded media and gadget programs with the 3D experience of worlds such as Second Life.

Lively began as a '20 per cent project' for Google engineering manager Niniane Wang. Google allows its employees to spend up to 20 per cent of their work time on their own projects.

"A while ago, I looked around the social web and wished that it could be less static," explained Wang.

"Sure, you can leave a comment on a blog or write a text blurb on your social networking profile. But what if you want to express yourself in a more fun way, with 3D graphics and real-time avatar interactions?"