Facebook has denied claims that a software bug caused private messages dating from 2009 to be displayed on profiles overnight, insisting that the messages were left in public originally, but that members have since become more privacy-conscious.
The social network was deluged with complaints from members who claimed their old private messages have been re-published publicly on the social network.
Facebook admitted old messages were reappearing on profiles but quickly denied that there had been a privacy breach, as the messages were old public messages.
It appeared that members were shown old public "wall" postings that they wrongly believed were private messages. Observers said the outcry showed how the way people use Facebook has changed, as they have become more aware of their privacy online.
Facebook’s director of engineering, Andrew Bosworth, aimed to calm the panic.
"In case there was any concern, these are just wall posts and not personal messages… people just forget how we used to use the wall!," he said.
Some users had claimed that messages they had sent privately on the social network between 2007 and 2009 were being republished into their public timelines on the site. Though it was not clear how many people were affected, there were complaints from users in Britain, America and in Europe.
Mark Zuckerberg, Facebook's founder and chief executive, was hit by the bug. His profile showed a message to a friend that said "2009 is going to be a huge year".
A Facebook spokesman said: "A small number of users raised concerns after what they mistakenly believed to be private messages appeared on their Timeline.
"Our engineers investigated these reports and found that the messages were older wall posts that had always been visible on the users’ profile pages. Facebook is satisfied that there has been no breach of user privacy."
Some were unconvinced by the denial, however. Colleen Taylor, a writer for an American technology website, said that she had confirmed with friends that messages appearing in their timelines were originally sent as private messages.
Last week, Facebook added a new feature that shows members of the site their search history and lets them delete searches they do not want Facebook to retain. The feature is part of Facebook's Activity Log, which lets members of the social network see what information Facebook holds on them.
Facebook said: 'It's important to remember that no one else can see your Activity Log, including your search activity."
One Facebook user in London said last night messages from 2006 to 2008 which had been sent to her by other users had appeared on her wall and messages she had sent as private were showing up on her friend’s wall.
She said: “This is worrying. I’m trying to figure out how to fix it. It’s scary. They are private messages and my friends and I used to dicuss private things on facebook.”
One user wrote on Facebook: “It happened to me and I’m in London. Having checked a few other people, I’m now wishing I hadn’t!”
Another added: “This Facebook Message thing is a huge mess. Confirmed for me. Found some private messages fully exposed on my timeline.”
Facebook has recently added a new feature that shows members of the site their search history and lets them delete searches they do not want Facebook to retain. The feature is part of Facebook’s Activity Log, which lets members of the social network see what information Facebook holds on them.
The greater emphasis on search has been interpreted as a bid by Facebook to take on the might of Google. Zuckerberg said: “Facebook is pretty uniquely positioned to answer the questions people have.”
Facebook agreed to turn off the feature in Europe. The feature has long been controversial and was turned on by default last year, meaning that users who did not want to be identified would have to opt out.
Earlier this year, Facebook angered some of its members when it forced them to adopt a new Timeline page, changing the layout of all the photos and messages they had ever posted to the social network. When the feature was first launched, in September last year, it was a voluntary feature but Facebook began making it compulsory in January.
