The President of the Australian Senate has informed the Government he believes he is a British citizen and may need to resign.
One of the country's most senior parliamentarians, Tasmanian Senator Stephen Parry is now the eighth MP caught up in the citizenship scandal that has engulfed parliament.
Senator Parry said his father moved to Australia as a boy in 1951.
"I have always regarded my late father as Australian, particularly as he undertook his national service and participated as a member of the Australian Army Reserve and voted in every Australian election since adulthood," he said in a statement.
Parry said he wrote to the British Home Office seeking clarity on the status of his citizenship with the United Kingdom. He was asked to provide further details and is waiting for a response.
"Depending upon the outcome, I may seek further legal advice before reporting back to the Senate. In any event I will report the result of the investigation and any subsequent advice to the Senate.
In the event he is in breach of Section 44(1) of the Constitution, Parry said he would resign as President of the Senate.
"I would further resign as a Senator for the State of Tasmania and not await the outcome of any referral to the High Court, as I believe the High Court has made it abundantly clear what action is required."
Senator Parry's disclosure is likely to reignite demands for all MPs and Senators to have their citizenship audited.
Comment is being sought form Senator Parry's office.
Meanwhile, the Acting Leader of the Opposition Tanya Plibersek criticised the Turnbull government in light of Parry's admission, saying the Coalition "is lurching from crisis to crisis".
"It's extraordinary that the President of the Senate -- who oversaw several High Court referrals -- did not reflect on his own eligibility until just days ago," she said.
"Malcolm Turnbull famously said that a failure to resolve eligibility issues showed "incredible sloppiness" and "extraordinary negligence. Mr Turnbull has shown terrible judgement throughout this sorry citizenship saga.
"Malcolm Turnbull must tell Australians whether he knew there were doubts over Senator Parry's eligibility. This revelation now raises questions about the Liberal Party's negligence when it comes to proper vetting processes."
The new development comes a week after several MPs were ruled ineligible to sit in Parliament by the High Court.
As a result, Labor believes more than 100 Turnbull Government decisions are vulnerable to legal challenge.
The opposition has received legal advice on a range of decisions which could be challenged after the High Court disqualified Joyce and senator Fiona Nash from Parliament.