SENATOR Stephen Parry has announced his resignation from Parliament after being informed he is a British citizen.
Senator Parry made the announcement moments ago.
"With a heavy heart I inform you that I have received advice from the British Home Office that I am a British citizen by virtue of my father's birthplace, thereby being a dual citizen under the provisions of the Australian Constitution.
"Now that the High Court's recent ruling has given absolute clarity to the meaning and application of Section 44(1) and as required by Section 17 of the Constitution, I will submit my resignation as both President of the Senate and as a Senator for Tasmania to His Excellency the Governor-General tomorrow."
Senator Parry said because his departure was rapid and an unexpected event he would not have the opportunity to address the Senate again.
"During my six and half years in the roles of Deputy President and President, I have closely observed the function and work of the Senate. The public do not see the hard work, countless hours of sitting, travel and debate and the toll it takes on family and friends."
Senator Parry wished his successor all the best.
"I trust that she or he will continue with the reforms that I have commenced, particularly in attaining greater independence from the Executive by way of an independent funding model for all of the parliamentary departments," he said.
EARLIER: ACTING Labor Leader Tanya Plibersek says it seems "very strange" that Senate president Stephen Parry had not thought about his eligibility to be a Parliamentarian until yesterday.
She said Senator Parry had overseen the referrals of a number of Senators to the High Court.
"These revelations are extraordinary," she said. "What is really interesting is when the Prime Minister knew that Senator Parry might not be eligible to be in the Senate.
"Senator Parry presided over a number of Senators being referred to the High Court.
"The notion that at no time did he consider that he himself might not be eligible is very difficult to understand.
"It is also difficult to comprehend that the first time he mentioned this to other members of the Government was today or yesterday."
In July the Mercury asked all Tasmanian politicians whether they were dual nationals (see below).
Senator Parry, who as Senate President earns $350,000 a year, replied via a spokesman that he was born in Burnie.
He did not address the question of dual citizenship.
Senator Parry said on Tuesday that he was waiting for the outcome of the High Court case and would resign if found to be a dual national.
The Mercury has today again asked all Tasmanian MPs to confirm that they are not dual nationals.
Ms Plibersek said Senator Parry should stand aside from his position as President of the Senate.
Senator Parry has written to the British Home Office seeking advice on whether he holds British citizenship.
WHAT THEY SAID IN JULY
GREENS Senator Nick McKim is 100 per cent certain he has renounced his British citizenship and won't be forced to resign from the Senate such as colleagues Larissa Waters and Scott Ludlam.
Senator McKim, who was born in Britain, took action to renounce before he took up a casual vacancy in 2015.
Senator McKim said he had fulfilled the High Court's criteria that he had done everything he reasonably could to renounce dual citizenship.
He said he had taken legal advice and filled out the British Home Office's form. While he received no confirmation from Britain "they took the money out of my bank account".
Senator McKim came to Tasmania aged 5 and became a naturalised Australian in 1985. He said the requirement Australian federal politicians had a singular allegiance to Australia was reasonable to ensure there was no conflicted allegiance if the nation went to war.
Greens Senator Peter Whish-Wilson said he had never been a citizen of Singapore despite being born there.
"This issue was examined during my preselection process," he said.
Liberal Senator Eric Abetz was born in Germany but renounced his German citizenship in December, 1974, before entering Parliament.
In a statement to the Senate in 2010, Senator Abetz said he had written to German authorities in 1992 to clarify his position that he had renounced his citizenship in 1974.
Other Tasmanian MPs confirmed their eligibility. Senator Jacqui Lambie said she was a "born and bred Tassie girl".
Liberal Senators David Bushby and Jonathon Duniam said they were born in Launceston. Senate president Stephen Parry was born in Burnie.
Labor Senators Helen Polley, Anne Urquhart, Carol Brown and Catryna Bilyk said they were Australian citizens.
Senator Lisa Singh said she had unknowingly been a British citizen via her father who came to Australia from Fiji.
"The Labor Party did due diligence on my citizenship status before I stood for the Senate in 2010 ... I had no awareness that the British citizenship had been conferred on me," she said.
Lyons MP Brian Mitchell was born in Britain but renounced his British citizenship in 2012. Braddon MP Justine Keay was born in Tasmania and obtained British citizenship in 2004 but renounced it before running for parliament last year.
Denison MP Andrew Wilkie, Franklin MP Julie Collins and Bass MP Ross Hart said they were born in Australia.