The Australian journalist who investigated Barnaby Joyce's dual citizenship said he and the Australian Labor Party "got wind of the story" about the same time, but it was his questions that "kicked things off".
The Australian deputy prime minister discovered last week that he held New Zealand citizenship, which, under the Australian constitution, disqualifies him from serving in the country's parliament.
He has lodged papers to renounce his New Zealand citizenship, and asked Australia's High Court to make a ruling on his eligibility to sit in parliament.
The discovery followed inquiries by the Australian media, and parliamentary questions from New Zealand Labour MP Chris Hipkins on citizenship rules for people born in Australia of New Zealand parents.
Yesterday, Labour party leader Jacinda Ardern told the Australian High Commissioner Mr Hipkins' actions were unacceptable, but ultimately reporters, and not the MP, uncovered Mr Joyce's dual citizenship.
Sydney Morning Herald political correspondent Adam Gartrell said his story was ready to go when Mr Joyce disclosed the possible problem on Monday.
The journalist told Morning Report he put questions to Mr Joyce's office, the New Zealand High Commission in Canberra and New Zealand's Department of Internal Affairs two days before Mr Hipkins' 9 August questions about dual citizenship.
Last Monday, he put a "hypothetical scenario" on citizenship to the New Zealand High Commission in Canberra, which said it passed it to Internal Affairs.
He followed up on the Wednesday, and every day after that, but was told they were still working on it.
"We now know there was a lot going on behind the scenes when I was waiting for that response."
Mr Gartrell said an Australian Labor Party senator's chief of staff contacted the New Zealand MP about citizenship laws but did not mention Mr Joyce.
"And meanwhile, also, the New Zealand High Commissioner here was paying a visit to Barnaby Joyce and telling him he might have a problem.
"I've been told by numerous sources that it was our questions that kicked things off," he said.
"It seems like the ALP [Australian Labor Party] here probably got wind of the story at the same time I did and started making their own inquiries."
"I think there were two parallel investigations going on."
The newspaper on Monday morning told Mr Joyce's office they were about to publish, and on that day he made his announcement in the Australian parliament.
Australian ministers accuse opposition parties of collusion
There were rowdy scenes in the Australian parliament yesterday as Prime Minister Malcolm Turnbull accused the Australian Labor Party and New Zealand Labour of collusion.
Foreign Minister Julie Bishop earlier accused the Australian Labor Party of trying to use the New Zealand parliament to undermine the Australian government, saying it put the relationship between the two governments at risk.
"New Zealand is facing an election, should there be a change of government I would find it very hard to build trust with those involved in allegations designed to undermine the government of Australia."
Mr Gartrell said it was a "really silly move" for Ms Bishop to say she would struggle to trust a Labour government, and amounted to intervening in an ally's election.
"Saying that she couldn't trust New Zealand Labour if they won the election I think was a pretty bonkers thing to say to be honest.
"It certainly blew things up in a way that it needn't have been."
Internal Affairs Minister Peter Dunne said his department was first asked about Mr Joyce's citizenship by the Australian media, not the Labour Party.
RNZ has asked the Department of Internal Affairs when it was first made aware of the matter. It said it would treat the question as an Official Information Act request, meaning it has 20 working days before it must respond.