The Australian Labor Party was fishing for information about New Zealand citizenship "weeks ago'', according to New Zealand Labour MP Chris Hipkins, who has found himself in the middle of a transtasman political scandal.
The opposition frontbencher has been blasted for a lack of judgement after asking citizenship questions linked to Australian Deputy Prime Minister Barnaby Joyce's parliamentary eligibility.
The High Court in Australia will determine later this month if Mr Joyce, a New Zealand citizen by descent through his father, is in breach of the Australian Constitution's prohibition on dual citizen MPs.
Last night it was confirmed Mr Joyce was no longer a New Zealand citizen. He received the paperwork confirming his renunciation yesterday.
The New Zealand High Commission and Department of Internal Affairs had notified Mr Joyce of his citizenship last week, after inquiries from Fairfax Australia and Mr Hipkins on Monday and Wednesday respectively.
Labour has tried to downplay Mr Hipkins' involvement, saying the media inquiries uncovered Mr Joyce's citizenship - a claim backed up by Internal Affairs Minster Peter Dunne.
But Mr Hipkins has admitted an ALP friend and associate raised the citizenship question "a couple of weeks ago''.
Labour leader Jacinda Ardern confirmed that person was an ALP staff member.
"I know they were a staffer. To be honest, I do not know their exact role but I don't believe they work for [Labor leader] Bill Shorten,'' she said.
The ALP's involvement has led Australian cabinet minister Christopher Pyne to accuse the opposition ALP of stooping to new lows.
"Clearly the Labor Party are involved in a conspiracy using a foreign government, in this case New Zealand, to try and bring down the Australian Government,'' he said yesterday.
New Zealand First leader Winston Peters described the contact between the ALP and Labour distasteful collusion on a "political hit job''.
He also took aim at Mr Dunne for "corroborating information that had obvious political intent''.
Mr Hipkins claimed he did not know whether the staffer's question related to a specific person.
"If that person knew where it was going to land up then it would have been useful to know,'' he said, adding while he has not asked that person since if they knew he still "may do''.
But he also plans on steering clear of the issue after incurring the wrath of Ms Ardern.
"Regardless of what information was known this was not an appropriate question for us to be asking or to be involved in,'' she said.
Prime Minister Bill English also criticised Mr Hipkins' judgement, saying he could not remember a time a New Zealand MP had involved themselves in another country's politics.
Mr Hipkins acknowledged his lesson had been learned.
"I should have given it more thought ... Probably the lesson for me in this is where it potentially might involve the politics of another country, a little bit more homework and background checking before getting involved would be a useful thing to do.''
