More than 60 diplomatic staff or family members have sought immunity for offences committed in New Zealand in the past 20 years, including for 25 serious criminal matters of a sexual or violent nature.
New Zealand officials applied to have diplomatic immunity waived in 13 of these cases, which range from drink-driving to assault, and a waiver was granted on seven occasions.
The new figures were revealed yesterday in an inquiry into how Malaysian diplomat Mohammed Rizalman bin Ismail was allowed to leave the country after being charged with sexual crimes.
The report's author, ex-Treasury Secretary John Whitehead, said offending by diplomats and family members in New Zealand was quite rare - around 2.3 incidents a year once minor offences were excluded.
But Mr Whitehead urged the Ministry of Foreign Affairs (Mfat) to be more open about future incidents involving diplomatic staff.
"In my view, greater transparency on such events and their aftermath in New Zealand ... would do much to enhance public confidence in the ministry's handling of these matters," he said.
This could involve annually publishing incidents, including the diplomat's country and offence but not their identity.
An Mfat spokeswoman said the ministry was "looking at how we can provide further information to the public on immunity issues".
The most infamous diplomatic offender in recent history was Australian navy officer Mark Napier, who waived his right to immunity in New Zealand in 2010 after being found with 40,000 objectionable images.
Greater transparency on immunity cases was one of 21 recommendations for Mfat in the Whitehead report, most of which have already been implemented.
The inquiry concluded that a single email was at the heart of a high-level misunderstanding which led the Malaysian Government to believe Rizalman could return to Malaysia with immunity in May 2014 after being charged.
That email, by protocol officer Mary Oliver to the Malaysian High Commission, said if Rizalman left before his first court appearance, "that would be the end of the matter".
Rizalman returned to Malaysia 12 days later, against the wishes of the New Zealand Government, police and the victim of his assault, Wellington woman Tania Billingsley.
No one in government or at Mfat will face disciplinary action. Ms Oliver left Mfat last year. Then-chief executive John Allen offered his resignation at the time, which was not accepted by Foreign Affairs Minister Murray McCully, and he has since left his post.
Labour Party foreign affairs spokesman David Shearer said yesterday it "defied belief" that an email about Rizalman's departure went unseen by Mr McCully for several weeks. The report absolved the minister of blame, saying his office failed to pass on details about the case. Mr McCully said he took responsibility and reiterated his apology to Ms Billingsley.
Diplomatic offences in NZ
• 25 serious crimes (including alleged violent and sexual offences)
• 11 drink-drive cases (including refusal to undergo a breath test)
• 11 traffic offences (speeding, not stopping at a red light, negligent driving)
• 10 minor criminal matters (shoplifting, disorderly behaviour)
• 3 civil matters (bankruptcy, business disputes)
• 2 unresolved parking fines
• 13 instances where waiver of immunity sought
• 7 instances waiver was granted