Facebook has raised privacy concerns again among some users by launching a feature that can show the relationship between two friends through the public information they've shared between each other.

Called "Friendship Pages," the feature, which is being rolled out gradually, would be accessible through a link under relevant Wall posts, relationship stories and the main photo on a person's profile page. Clicking the link would launch a standalone page that would include public Wall posts between the two people, photos in which both are tagged, events they have RSVP'd for together, mutual friends and mutual "likes."

Friendship Pages could only be retrieved by someone who is a friend with at least one of the two people and who has permission to view both their profiles. "When it's between two people who share a lot, the page really starts to reflect their friendship," Wayne Kao, the Facebook software engineer who developed the feature, said on the company's blog Thursday.

The new feature did draw concerns from some Facebook users. "While I'm all for innovation, privacy should come first," Rob Ahnemann, said on the comments section of Kao's blog. "If you introduce a new feature, notify the community when it arrives. (And) give a clear opt-in or opt-out button."