Australia Deputy PM Baa-naby's Kiwi Woes Create Chaos in Canberra

Sydney: Australia's top court will this week examine a constitutional crisis threatening to topple the conservative government, after parliament's attempts to deal with it ended in sheep jokes and conspiracy theories.

At least three senior government figures, including Deputy Prime Minister Barnaby Joyce, have been snared by a previously obscure constitutional provision that bars dual citizens from sitting in parliament.

With the government's one-seat majority on the line, Joyce has refused to stand down, arguing he previously had no idea he automatically inherited New Zealand citizenship from his Dunedin-born father.

The Australian-born deputy leader's case will go to the High Court on Thursday, along with four other politicians who have unwittingly found themselves on the wrong side of the law.

A sixth lawmaker, National Party senator Fiona Nash, is also set to join the court case after discovering late last week she was a dual Australian-British citizen.

Professor Don Rothwell, a constitutional expert from the Australian National University, said the stakes in the case were high.

"One possibility, albeit remote as it stands at the moment, is that the government of the day could fall... in which case we could see an election called," he told AFP.

The dual citizenship provision was inserted in the 1901 constitution to ensure parliamentarians had no "adherence to a foreign power".

Rothwell said it was framed at a time when Australians still believed their primary loyalty was to the British crown, and appeared increasingly archaic in an immigrant nation such as Australia.

"It has this time-warped understanding of what foreign powers were from 1901," he said.

"A much more liberal approach is taken (in the community) towards dual citizenship these days."

Tinfoil hats, treason!

Much will rest on whether the High Court adopts the same approach or takes a narrower view of the constitution's section 44(i).

Regardless, the court will certainly give the issue more sober consideration than Australia's politicians, who turned Canberra into a sideshow after Joyce dropped the bombshell Monday that he was a Kiwi citizen.

Prime Minister Malcolm Turnbull seized upon the fact that a member of New Zealand's Labour Party asked questions about the citizenship issue the previous week to allege a grand plot to bring him down.

Opposition leader Bill Shorten of the Australian Labor party was attempting "to steal government by entering into a conspiracy with a foreign power", Turnbull thundered.

Foreign Minister Julie Bishop accused Shorten of "treacherous behaviour" and said she would find it hard to trust New Zealand Labour if it won the country's elections next month.

"(It) is not only highly improper but is in direct breach of the international obligation for non-interference. Labor have now been well and truly caught out," Bishop said.

Labor's Penny Wong accused Bishop of running "a Kiwis under-the-bed scare campaign", invoking anti-communist "Reds under the beds" fears of the Cold War.

Her colleague Rob Mitchell turned up in parliament holding a tinfoil hat, which he said was for Bishop.

"Sounds like Julie's on the phone now," he told reporters as his mobile went off with the ringtone playing the theme to "The Twilight Zone" television show.

"She's been on to NASA and Area 51 at Roswell claiming that it's all our fault about Barnaby Joyce," he told reporters.

Meanwhile, Joyce's status as an accidental Kiwi led to inevitable sheep jokes, never far from the surface when Australians discuss their trans-Tasman cousins.

Joyce endured taunts of "Baa-naby" from the opposition benches, while Bishop was told "you've just jumped the sheep!" after outlining her Kiwi conspiracy.

Rothwell said the High Court was likely to expedite its judgement on the citizenship saga due to its potential impacts.

But he said a ruling in the case, due to start at a preliminary hearing on Thursday, was likely to be weeks away.

In the meantime, Australians can look forward to their representatives in Canberra continuing to snipe at each other as they scramble to check they have no citizenship skeletons in the closet.

As the Kiwis would say when expressing approval over something "choice, bro'".