Australia's government accuses New Zealand of 'conspiring' against it

Australia now has another reason to hate their closest rival, New Zealand.

New Zealand's opposition Labour Party is part of a "conspiracy" to bring down the Australian government -- at least according to Australia's governing Liberal National coalition.

The diplomatic clash caps off a bizarre 48 hours in Canberra after Australia's deputy prime minister Barnaby Joyce was discovered to be a New Zealand citizen through his father.

Citizens of foreign countries are not allowed to sit in the Australian Parliament, according to the country's Constitution, a rule which has already tripped up a number of politicians in recent months.

It's a confusing situation which only got more complicated when it turned out a New Zealand Labour politician, Chris Hipkins, had asked about a situation very similar to Joyce's in the New Zealand Parliament just a week before.

Speaking to a meeting of all government politicians on Tuesday morning, Australian prime minister Malcolm Turnbull accused the Australia's opposition Labor Party of "conspiring" with their New Zealand counterparts, local media said.

"We have learned this morning the Australian Labor Party has been conspiring with the NZ Labour Party to undermine the position of the deputy prime minister and the government of Australia," he said.

Along with their close diplomatic relations, Australia and New Zealand have had a long-running friendly rivalry covering sport, food and even the occasional joke on "Flight of the Conchords."

But the worse could be yet to come for Turnbull -- his government only has a one seat majority and if Joyce is forced out of parliament it could undermine his hold on power.

What the hell is going on in Australia? Here's everything you need to know:

Who is Barnaby Joyce?

Joyce is the deputy prime minister of Australia and has been since February 11 when he was elected head of the National party, the junior partner in Australia's governing coalition.

He's also the nemesis of actor Johnny Depp whose dogs, Pistol and Boo, Joyce threatened to euthanize in April 2016 after they were brought illegally into Australia.

Depp and his then-girlfriend Amber Heard made a famously awkward apology video at the request of the Australian government, in which they said "protecting Australia is important."

He told parliament on Monday morning he had discovered he was a New Zealand citizen, potentially throwing his position in parliament into jeopardy.

His case has been referred to the High Court of Australia, who will decide whether or not he must resign.

It's a bitter revelation for Joyce, not just because of the potential consequences for his career but because he was so sure when asked earlier.

"I'm born in Tamworth Base Hospital, where my great-grandmother was born 100 years before me, and I am an Australian, no problems there," he told Channel Nine's Today Show.

Wait, why is that a problem?

Members of Australia's national parliament can't be citizens of another country, according to section 44 of the country's constitution.

It's an archaic law, especially now that a quarter of Australia's population was born overseas and another quarter have parents who were born overseas.

In Joyce's case, his father was a New Zealander, which according to a New Zealand government website, means he is "an New Zealand citizen by descent."

Joyce is not the first Australian politician to get caught on this technicality in the past few months.

In July, two senators in the Australian Greens stepped down from their positions after discovering they were a New Zealand and a Canadian citizen respectively.

Later the same month, government minister Matt Canavan resigned from his position, but not from the Senate, after he discovered he was an Italian citizen, something he blamed on his mother.

Unlike the Greens senators, Canavan and Joyce have refused to resign their positions and instead been referred to Australia's High Court.

Why is Australia mad at New Zealand?

Australia and New Zealand have previously shared a very close relationship -- they even considered briefly becoming one country in the early 1900s.

But on Tuesday a number of government ministers implied the New Zealand Labour Party had colluded with the Australian Labor Party to bring down Australia's government.

Foreign Minister Julie Bishop said she would find it "very hard" to trust a Labour government in New Zealand now.

New Zealand Labour leader Jacinda Ardern confirmed on Tuesday afternoon a staffer in Australian Labor had contacted her party, but said "Australian domestic politics is for them, not us."

The country's Internal Affairs minister Peter Dunne said it was "utter nonsense" to suggest New Zealand's opposition party had triggered Joyce's problems. "They were not the instigator. Australian media inquiries were," he said on Twitter.

In spite of everything, Nick Economou, senior lecturer in Australian politics at Monash University, told CNN he was sure the Australia New Zealand relationship would be able to withstand the current diplomatic tiff.

"I'm sure that everyone understands this is robust parliamentary politics ... I would think one of the things that might help in a New Zealand election campaign is to be roughed up by Australians and to be resolute in your defense against them," he said.

Where to from here?

The only way to resolve the citizenship issue would be to change the Australian Constitution, which would require a national referendum. There were calls for it to be changed in 1997 but the government of the day let the matter fade from view.

"It hasn't (come up) until now because the two parties have had a mutual interest in not bringing it up," George Williams, dean of Sydney University Law school, told CNN.

"There may have been issues but they just knew that either party might be attacked on these grounds, so they just hadn't pursued it."

But now it is out in the open, it is highly likely the citizenship clause will trap even more Australian politicians on all sides of parliament, Economou said.

"At some point it will go from being a minor irritant to a major problem because if they start to sift through the phalanx of MPs and look at the ones who have been the children of immigrants, we're going to end up threatening a whole bunch of careers," he said.

Williams said it was likely both cases before the High Court, Canavan's and Joyce's, would not be settled for months, possibly not until December.

Even then, there isn't any real idea about what the court will decide.

"If the High Court took a particularly generous interpretation of this, it might curb the eligibility problems of the senators and MPs, but that's a difficult thing to do given ... the section is quite clear," he said.

What do Johnny Depp and Amber Heard think about this?

So far Depp hasn't commented on the possible downfall of his longtime nemesis but Heard tweeted on Tuesday she had sent Australia's deputy leader a box of kiwi fruit to celebrate his new found heritage.

"Assuming this passes his biosecurity laws," she said, jokingly.