Five of the seven federal politicians who fell foul of Australia citizenship rules have been disqualified from Parliament, including the country's deputy Prime Minister.
Australia's High Court ruled on Friday that Australia-born Deputy Prime Minister Barnaby Joyce - who had New Zealand citizenship from his father - is ineligible to remain in Parliament, a decision that has cost the coalition government its one-seat parliamentary majority.
Mr Joyce was one of seven politicians whose eligibility to sit in parliament was thrown into doubt when it was found they were dual citizens, which bars them from being elected to the national Parliament under Australia's constitution.
Speaking to the media in Tamworth, Mr Joyce said he respected the court's verdict and apologised for the inconvenience the by-election would cause.
"I was always prepared for this outcome. I don't actually stand here totally surprised.
"I always expected that this was going to be a tough game," he said.
He said he hoped the writs would be issued today and the by-election could be held in early December and, now that he had renounced his New Zealand citizenship, he would nominate.
It leaves Prime Minister Malcolm Turnbull's centre-right coalition in the precarious position of a minority government. Mr Turnbull's Liberal Party is the senior party in a coalition with the smaller National Party, which Joyce led.
Mr Turnbull must now win the support of one of three independent lawmakers to keep his minority government afloat, with two sitting weeks of Parliament left until it recesses for the year.
The court ordered that a by-election must be held for Joyce's New England electorate. The Australian dollar fell a quarter of a US cent after the court announced its decision.
Section 44 of the Australian constitution bans dual citizens from being eligible for election.
Those ruled ineligible to sit in Parliament by the High Court in Australia are: deputy Prime Minister Barnaby Joyce, former senator Scott Ludlam, deputy Nationals leader Fiona Nash, former Greens senator Larissa Waters, and One Nation senator Malcolm Roberts.
Nick Xenophon and Matthew Canavan are safe, the High Court ruled.
Deputy Prime Minister Barnaby Joyce revealed to Parliament in August his father was born in New Zealand.
Despite emigrating to Australia before his son was born, New Zealand law made Mr Joyce a Kiwi by descent.
He has since renounced his New Zealand credentials.
Matt Canavan resigned from the Turnbull ministry when he discovered he may have been an Italian citizen by descent, through his Italian-born grandparents.
Fiona Nash, Deputy Nationals Leader, learnt she was a UK citizen by descent, because her estranged father was born in Scotland.
She argued she did not know, because she'd had minimal contact with her dad growing up - but she did understand her sisters, who were born in the UK, were dual nationals.
The High Court has already ruled One Nation party member and Senate crossbencher Malcolm Roberts was still a British citizen at the time of the 2016 federal election, after being born in India to a Welsh father and an Australian mother.
The former Greens senators Scott Ludlam and Larissa Waters had already left their seats and south Australian crossbencher Nick Xenophon has signalled plans to quit to run in next year's state election.
- ABC / Reuters