Fresh questions have arisen over the dual citizenship of One Nation senator Malcolm Roberts.
News site Buzzfeed has obtained documents showing Senator Roberts' name in a UK High Commission birth index which notes his Indian birthplace.
He is also listed as having travelled by ship on a British passport with his parents when he was a young child.
The Queensland senator was born in India to a Welsh father.
Under Section 44 a person is disqualified from being elected if at the time of their election they are a citizen of "a foreign power" or otherwise have an "allegiance, obedience or adherence to a foreign power".
Two Greens senators have resigned after discovering their pre-existing foreign citizenship and the High Court is expected to look at a third senator, Queensland's Matt Canavan, who stood aside from cabinet after discovering he had Italian citizenship.
Senator Roberts, who is seeking an inquiry into the citizenship issue, has said that prior to running as a One Nation candidate in 2016 he "fully investigated" whether he was eligible to sit in parliament.
"In 2014 I contacted the Indian authorities and that confirmed I am not an Indian citizen," he tweeted last week.
"I am a citizen only of Australia."
On Friday, he signed a statutory declaration in which he added to his Twitter comment.
"As part of my investigation I analysed if I was a British (United Kingdom) citizen by decent (sic) from my father, who was born in Wales, the United Kingdom, or if I was an Indian citizen.
"I can confirm I am not a citizen of the United Kingdom, nor am I citizen of India. I am a citizen of Australia only."
Senator Roberts has declined to release documents relating to his renunciation, including its timing.
Former prime minister Tony Abbott two years ago released a letter from UK Visas and Immigration confirming he had renounced his British citizenship in October 1993.
Defence Minister Marise Payne encouraged Senator Roberts and any other MPs facing citizenship question to provide all evidence to "shine a light" on their positions.
"I would have thought that making the position as clear as possible is the best way to go," Senator Payne told ABC radio.
"I'm not going to direct or instruct any senator on what they should do - they are decisions for themselves - but I would have thought that the greater light that is shone, the greater clarity that is available, the better."
