Deputy Prime Minister Barnaby Joyce has revealed that he may be a citizen of New Zealand - and unable to serve in Parliament - after being informed of the potential issue by the New Zealand High Commission.
According to section 44 of the Constitution Senators and members of Parliament are forbidden from being citizens of a country other than Australia.
Mr Joyce - whose eligibility will be referred to the High Court - won't be stepping aside from cabinet, unlike his Nationals colleague Matt Canavan who discovered his mother signed him up for Italian citizenship.
Mr Joyce said the federal government, based on legal advice from the Solicitor-General, is of the firm view he is not in breach of section 44 of the constitution - which bars dual citizens from sitting in parliament.
'Given the strength of the legal advice the government has received, the Prime Minister has asked that I remain as Deputy Prime Minister and continue my ministerial duties'.
The New Zealand High Commission contacted the Nationals leader on Thursday afternoon to advise he may be a citizen by descent.
The second most senior politician in Australia is the latest to be caught up in the parliamentary citizenship scandal which has claimed the scalps of several senators and possibly several more.
This news follows the shock resignation of Greens senators Scott Ludlam andLarissa Waters over their dual-citizenships.
"Neither my parents nor I have ever applied to register me as a New Zealand citizen, the New Zealand Government has no register recognising me as an New Zealand citizen", he said.
'I was born in Tamworth, just as my mother and my great-grandmother was born there 100 years earlier, ' he told parliament on Monday morning.
The Government holds a one seat majority in the House of Representatives and if Mr Joyce were disqualified from being able to sit in Parliament, the government would lose its majority.
But in any case he asked the government to refer him to the High Court.
Joyce was born in Australia.
Several senators have resigned or are facing scrutiny over their citizenship status.