Australia's justice minister Michael Keenan is facing questions over whether he is a British citizen by descent.
He is the third Australian federal government minister to be enveloped in widening dual citizenship turmoil.
People with foreign citizenship, or entitled to foreign citizenship, are not eligible to sit in the Australian parliament.
Deputy Prime Minister Barnaby Joyce renounced New Zealand citizenship just days ago, while Resources Minister Matt Canavan resigned his cabinet post last month when it was revealed his mother applied for an Italian passport on his behalf.
Mr Keenan's father was born in the UK, but he said he was an Australian citizen.
"I am an Australian citizen and do not hold citizenship of any other country," Mr Keenan said.
"I renounced my [British] citizenship in 2004 before entering parliament."
The High Court has already been asked to decide whether five parliamentarians were validly elected.
Greens deputy leaders Scott Ludlam and Larissa Waters resigned from parliament over their dual citizenship and One Nation's Malcolm Roberts will also face a court ruling.
Mr Joyce said he would recontest his seat of New England should the High Court rule he was invalidly elected.
Mr Joyce has told Sky News he was "shell shocked" when he discovered he was a dual citizen, but had since renounced his New Zealand citizenship.
He defended his decision not to resign from the cabinet and said he would fight to remain in parliament.
"I've got no reason to pull out now. I've worked really hard to get myself in a position where I can do all these things. Now I want to see them through," Mr Joyce said.
The citizenship controversy has included a diplomatic spat between the Australian government and the Labour Party in this country.
Australian media were inquiring into Mr Joyce's citizenship but New Zealand Labour MP Chris Hipkins had also asked similar questions to the New Zealand Internal Affairs Minister, following discussions with a friend who worked for an Australian Labor senator.
- ABC / RNZ