The Taoiseach Enda Kenny has confirmed to the Dáil that phone calls between 84 prisoners and legal representatives were "inadvertently recorded".
The Taoiseach said the disclosure came to light during this morning's Cabinet meeting.
The Justice Minister Alan Shatter has asked for a report "on how this happened".
The Prison Service was aware of the problem on Wednesday of last week - but it was only communicated to Minister Alan Shatter in the middle of today's Cabinet meeting.
Mr Kenny has now demanded a report on the issue from the prison service.
Meanwhile, The Taoiseach has confirmed that the Garda Commissioner was required by law to inform both the Justice Minister and the Department's Secretary General of the problem of the Garda tape recordings.
Mr Kenny says the issue was not raised by the Secretary General who had received the letter at the crisis meeting to discuss the problem eight days ago.