Many Finnish users reported on Monday that private messages sent before 2009 had somehow been added to their public profile. There were no reports of the same thing happening outside of Finland.
Facebook says that what users had thought were private messages were actually discussions on users' walls, where the message chain looks similar to a private messaging conversation but is actually visible to other users as well.
The issue relates to the Facebook Timeline feature, which was officially released one week ago. Timeline allows users to add old events, updates, photos and messages to their profiles, but some Finnish users claimed to have found their private messages among the information unwittingly made public.
The company says that the information was already public, if quite old, but the timeline feature has pushed older activity to the fore in Facebook profiles.