An urgent investigation is being conducted into Foreign Minister Murray McCully's decision to withhold documents relating to the Malaysian diplomat accused of assault with intent to rape.
McCully refused an Official Information Act request from Newstalk ZB in July. It had sought copies of advice and correspondence relating to the use of diplomatic immunity by Malaysian defence attache Muhammad Rizalman bin Ismail.
Chief Ombudsman Dame Beverley Wakem agreed to urgently investigate McCully's decision on the release of the documents after Newstalk ZB's parent company, the Radio Network, complained to the ombudsman.
Rizalman was arrested on May 9 after allegedly following a 21-year-old woman home and assaulting her in the Wellington suburb of Brooklyn, where the Malaysian embassy is located.
He was charged with burglary and assault with intent to commit rape.
Malaysia refused to waive Rizalman's diplomatic immunity and he left New Zealand on May 22.
Controversy surrounded the case, after officials from the Ministry of Foreign Affairs appeared to have given an ambiguous impression to Malaysian officials on New Zealand's position that Rizalman should remain in the country.
A ministerial inquiry was announced into how the ambiguity was created and why Rizalman had been allowed to leave.
It will be headed by John Whitehead, who was secretary to the Treasury from 2003 to 2011.
Rizalman's psychiatric evaluation has recently been completed, with a view to returning him to New Zealand to face trial.
The chief of the Malaysian armed forces has said the timeline of Rizalman's extradition was a matter for the two countries to determine.