New Zealand ask Australia for the unthinkable - after late night incident in Wellington

Authorities in New Zealand have taken the rare step of asking Australia to waive immunity for a diplomats partner allegedly involved in a boozy fight after a Bledisloe Cup Test.

An altercation between three people in downtown Wellington about 3.30am on Sunday attracted the attention of local police.

The incident has been described privately to AAP as a drunken punch-up involving the male partner of an Australian diplomat stationed in the Kiwi capital, who was wearing Wallabies gear.

Police took one person into custody who was later released without charge after it was confirmed they held diplomatic immunity, an NZ Police spokeswoman said.

Dixon St, the location of the incident, has popular pubs and two strip clubs.

The identity of the man has not been released but its understood the person involved is not the partner of Australias High Commissioner in Wellington, Harinder Sidhu.

Australias Department of Foreign Affairs and Trade has confirmed the matter without any specifics, and has not provided public comment on the sensitive incident first reported by Sky News.

New Zealand authorities want the partner of an Australian official to lose his diplomatic immunity after he was involved in a post-Bledisloe Cup altercation.

The department lists 18 Wellington-based staff on its website, along with six male partners.

Sky News reported the man told police he was immune from New Zealand laws as he was being arrested.

Diplomatic immunity is a right afforded to representatives based overseas that allows them freedom to conduct diplomatic business without being arrested or detained.

Diplomats families are extended that same privilege during their overseas postings.

Owing to the seriousness of the alleged crime, New Zealand police confirmed they initiated a request to have immunity stripped from the man.

New Zealands Ministry of Foreign Affairs and Trade said it had contacted Australias High Commission over the incident.

It is the expectation of the government of New Zealand that foreign representatives and their accredited family members will comply with New Zealand laws and regulations, a ministry spokeswoman said.

A decision on whether to revoke immunity could fall to Australian Foreign Minister Penny Wong.

The piece of international law that sets guidelines for diplomats, the Vienna Convention on Diplomatic Relations 1961, dictates immunity can only be waived by the sending state, which in this case is Australia.

It is not yet clear whether Australia will do so, or how heavily New Zealand is pushing for immunity to be waived.

Such requests are rarely made and only granted exceptionally, Australian National University international law professor Donald Rothwell said.

It occurs only in rare instances ... and only when there is an exceptionally serious offence that has occurred, he told AAP.

The ball is in Australias court in terms of how it responds.

Another option is for Australia to simply withdraw the diplomat and partner from their posting, which removes the legal issue.

That diplomatic wrangling is likely to play out behind closed doors between officials, with politicians on either side of the Tasman declining to comment on Wednesday.

The incident came hours after another trans-Tasman contest: the second leg of this years Bledisloe Cup rugby union series.

The All Blacks defeated the Wallabies 33-13 at Sky Stadium, two kilometres north of where the altercation happened.

It was the ninth-straight All Blacks win over the Wallabies, confirming the Bledisloe Cup will remain in New Zealand for a 22nd consecutive year.