PALO ALTO, California: Privacy advocates are likely to be outraged by social networking website Facebook's decision to allow the site's unregistered users to find out the identities of profiled members.

And anger is expected to be further fuelled next month when Facebook opens its database to search engines such as Google and Yahoo!.

The firm says the information being released is minimal and will be restricted to name and photograph only. Members can also opt out of a public listing altogether.

A statement from Facebook says: "We're not exposing any new information, and you have complete control over your public search listing. We think this will help more people connect and find value from Facebook without exposing any actual profile information or data."

But critics are concerned that personal content will eventually be used for marketing or other purposes and security experts have highlighted the dangers of publicising dates of birth.

Facebook now accounts for one per cent of all web traffic. It is thought to have around 39 million members and is the sixth most visited site in the US.

Data sourced from Brand Republic (UK); additional content by WARC staff