The Australian Labor Party staffer who fished for information about New Zealand citizenship has been identified.
Senator Penny Wong's chief of staff Marcus Ganley, himself from New Zealand, spoke to Labour MP Chris Hipkins, Fairfax Media reports.
That conversation has plunged Mr Hipkins into the middle of a trans-Tasman political scandal.
He put in written questions it's now known were linked to Australian Deputy Prime Minister Barnaby Joyce's parliamentary eligibility, and he's been blasted by his party leader for his lack of judgement.
Senator Wong has confirmed it was one of her staff who had an "informal discussion" with Mr Hipkins.
The High Court 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.
The New Zealand High Commission and Department of Internal Affairs 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 told Sky News.
NZ 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 claims he didn't know whether the staffer's question related to a specific person.
NZ Prime Minister Bill English also criticised Mr Hipkins judgement, saying he couldn't remember a time before that a New Zealand MP had involved themselves in another country's politics.
