Deputy leader of the Nationals Fiona Nash is the latest politician to be ensnared by the citizenship fiasco, revealing she is a British citizen by descent.

Key points: Nash says she had little contact with her Scottish father, was told she was not a dual citizen

Nash says she had little contact with her Scottish father, was told she was not a dual citizen Revelation comes days after Barnaby Joyce revealed he was a citizen of New Zealand

Revelation comes days after Barnaby Joyce revealed he was a citizen of New Zealand Nash will not stand aside from portfolio responsibilities, will be referred to High Court

The revelation comes just days after the leader of her party, Deputy Prime Minister Barnaby Joyce, revealed he was a citizen of New Zealand.

Senator Nash said she had sought advice of the UK Home Office on her citizenship status after Mr Joyce's statement on Monday.

"By Monday evening, I was advised that a caseworker at the UK Home Office was of the view that, on the basis of the limited facts that I had provided, I was a British citizen by descent through my Scottish-born father," she said.

Senator Nash said her mother was born in Australia and was an Australian citizen, but her father was born in Scotland in 1927.

"I was born in Sydney in 1965. My parents divorced when I was eight and my mother raised me," she said.

"I had very little contact with my father throughout his life, and he died nine years ago. My mother died five years ago.

"Growing up, my parents always told me that I was not a dual citizen.

"My understanding since early childhood was that in order to be a dual British citizen I would need to apply for it.

"Indeed, an internet search reveals a host of websites that say having a Scottish-born father allows one to apply for citizenship, but mention nothing of automatic citizenship by descent."

Nash will not stand aside from portfolio

Senator Nash will now be referred to the High Court along with Mr Joyce, fellow Nationals senator Matt Canavan, One Nation senator Malcolm Roberts, and former Greens senators Scott Ludlam and Larissa Waters, who have already resigned.

She said she had spoken with Prime Minister Malcolm Turnbull and the Federal Government had sought advice from the solicitor-general.

"I can advise honourable senators, that on the basis of the solicitor-general's advice, the Prime Minister sees no reason for me to stand aside from my portfolio responsibilities," she said.

Senator Nash is the Minister for Regional Development and Regional Communications.

She has represented the Nationals in the Senate since 2005, and has served as deputy leader of the party since February 2016.

Nationals whip John Williams said he did not know Senator Nash's citizenship was in doubt.

"This is a decision for the courts and let's see how it all pans out — but thanks for the surprise," he said.

Sorry, this video has expired Barnaby Joyce said his legal advice suggests he has not breached the constitution.

Labor questions why Nationals held 'to lesser standard'

Labor senator Katy Gallagher said Mr Turnbull needed to explain why he not asked Mr Joyce and Senator Nash to stand down.

"Senator Nash's statement means the entire National Party leadership is now facing disqualification from the Parliament," she said.

"Malcolm Turnbull needs to explain why he is holding Mr Joyce and now Senator Nash to a lesser standard than Matt Canavan and not requiring them to stand down," she added.

Senator Gallagher said it was unacceptable Senator Nash had stayed quiet about her citizenship doubts since Monday.

"As Senator Nash admitted, she has known since Monday that she was a dual citizen, yet waited until one minute before the Senate rose for a two week break to inform the Parliament," she said.

"This is simply not good enough."