Social networking site Facebook is opening up its users' personal information to limited searches by non-members, with profiles on the site ultimately heading for search engines such as Google.

The site Wednesday announced it was making limited public searches of user profiles available to people who are not logged in to Facebook. Visitors to the site can search for people with profiles from Facebook's main page. Previously, a person had to have a profile on Facebook and be signed in to look for other people on the site.

Search results turn up only a person's name and current profile picture, and the person searching must log in to get any further information or to make contact. Users can also opt out of being included in the limited search by changing their privacy settings.

Facebook said it will expand the search to engines such as Google, Yahoo and MSN Live in a few weeks.

Phillip Fung, a Facebook engineer, wrote on the site that the change is being made to make it easier for people to find each other.

"The public search listing contains less information than someone could find right after signing up anyway, so we're not exposing any new information, and you have complete control over your public search listing," he wrote.

The site's move will likely renew concerns about personal privacy and security of information.

Facebook's popularity has skyrocketed since the site opened itself up beyond just college students last September.

With more than 39 million members, up 62 per cent from 24 million in late May, the site has marketers and advertisers salivating for ways to exploit its huge database of personal information.

Privacy has also been part of Facebook's success, where users' information has been relatively walled off from the rest of the internet, unlike other social networking sites.