Social network Facebook is planning to allow users to make their profiles on the website searchable by the public and enable search engines to index its members’ listings.

Facebook will notify its members of the move today, allowing them to choose whether or not they want their basic profile listings to be made public. Outsiders will only be able to view the name and public profile picture, it says.

Also, anyone who finds a listing via a search on the site will need to sign up to the network before they are permitted to make contact with a Facebook member. There are some concerns that user privacy may be compromised as this is an ‘opt out’ scheme.

The move is a search engine play intended to tempt more people to join the site. Given limited Google fodder it will be interesting to see whether Facebook will establish itself in the top ten results for name-related searches, alongside the likes of Myspace.

Facebook has until now had a stricter approach towards privacy than other social networks, many of which allow search engines to index their members’ listings. But it is under fire from some members over reported plans for a new contextual ad system

Several people search engines have been launched in the last year, many of which are using publicly available data from social network profiles. PeekYou and Spock both rely partly on social networks for their listings, and this move may concern such sites.

The fast-growing social network now has around 39m members, with its membership estimated to have risen by 62.5% from 24m in May this year.