The Foreign Minister is to be investigated over his decision to withhold papers relating to the Malaysian diplomat case.
In late July Murray McCully gave a blanket denial to an Official Information Act request seeking copies of advice and correspondence relating to the use of diplomatic immunity by Malaysian defence attache Muhammad Rizalman bin Ismail.
Ismail had been charged with burglary and assault with intent to rape, but left the country after diplomatic immunity was invoked.
Chief Ombudsman Dame Beverly Wakem has agreed to investigate Mr McCully's decision on an urgent basis.
Labour's foreign affairs spokesman David Shearer said the fact that Dame Beverley was stepping in showed the significance with which Mr McCully's actions were being seen.