Australian Deputy Prime Minister Barnaby Joyce is a New Zealand citizen, New Zealand Internal Affairs Minister Peter Dunne has confirmed.
The shock revealtion means he holds dual Australian and New Zealand citizenship and will likely be forced to resign.
Australian law bars dual citizens from sitting in parliament.
The New Zealand High Commission contacted Mr Joyce on Thursday afternoon to advise he may be a citizen by descent.
He said he was shocked to receive that information, adding he had been born in Tamworth and had always been an Australian citizen.
"Neither I nor my parents have ever had any reason to believe that I may be a citizen of any other country," he said on Monday.
While his mother was Australian, his father was born in New Zealand and came to Australia in 1947 as a British subject.
Mr Joyce asked the government to refer the matter to the High Court.
"Given the strength of the legal advice the government has received, the prime minister has asked that I remain Deputy Prime Minister and continue my ministerial duties," he said.
- Australian Greens co-deputy leader resigns after finding out he's still an NZ citizen
- Another Greens senator resigns over dual citizenship
It comes after both co-deputy leaders of the Australian Green party had to resign last month, when it was revealed they held dual citizenship.
Australian Greens co-deputy leader Scott Ludlam resigned after it emerged he holds dual citizenship of Australia and New Zealand, and Larissa Waters because she has dual citizenship with Canada.
Under section 44(i) of the Australian constitution, election to public office is ruled out for: "Any person who is under any acknowledgement of allegiance obedience or adherence to a foreign power, or is a subject or a citizen or entitled to the rights or privileges of a subject or a citizen of a foreign power."
NZN / Newshub.