An independent review initially considered adding an historic complaint against whistleblower Sgt Maurice McCabe to the terms of reference of the O'Higgins commission of investigation, but decided not to after reviewing the garda investigation files.

Almost €22m of taxpayers’ money will be spent by the end of the year on just six of the 15 investigations and tribunals that have been announced by Government.

A mammoth GSOC inquiry report regarding the Garda investigation into Ian Bailey could be published as early as this week.

It has understood that the Department of Justice is to establish a statutory inquiry into allegations of Garda misconduct made by a former head of the Irish Small and Medium Enterprises Association.