Twitter has revealed that a long hidden bug in its privacy settings has caused 93,788 protected accounts to show tweets to non-approved followers since November 2013. th

The micro-blogging site said the number of people affected by the bug was relatively small, about 0.00004%, compared to Twitter’s 115 million active users.

Twitter information security director Bob Lord said: "We were alerted to and fixed a bug in our system that, for 93,788 protected accounts under rare circumstances, allowed non-approved followers to receive protected tweets via SMS or push notifications since November 2013.

"As part of the bug fix, we’ve removed all of these unapproved follows, and taken steps to protect against this kind of bug in the future."

The latest fix also eliminates unapproved follows away from the protected accounts.

"While the scope of this bug was small in terms of affected users, that does not change the fact that this should not have happened," Lord said.

"We’ve emailed each of these affected users to let them know about this bug and extend our whole-hearted apologies."

Last week, the micro-blogging site experienced an error resulting in ‘accidental’ password reset notices to many users.