Facebook is kicking people out of their accounts and won't let them back in.

The issues appear to be the result of key parts of the Facebook infrastructure not working.

Some people are seeing strange alerts, like the site telling them that all of their messages have been deleted for being spam. Others are sent back to the login screen and then told that their accounts can't be verified.

Even more concerning messages seem to suggest that a users' account has been hacked and so they have been signed out or their password has been changed. Others request that people change their password because of an apparent hack, but that password will then not work as a way of getting into their account.

But in fact that appears to be the result of a failsafe that means that Facebook's security tools won't let people log in if there appears to be an issue with the servers that allow them to do so.

The problems are occurring across the world, according to the website Down Detector. In particular they are hitting Europe and the East coast of the US, but that might be a consequence of time zones rather than the geography of the problems.