Attorney-General George Brandis has been forced to eat his words as the Turnbull government is rocked by yet another citizenship bombshell, and a legal expert warns it may not be the last.

Senate President Stephen Parry, whose father was born in the UK, said on Tuesday he had sought advice from the Home Office over his possible British citizenship and would quit Parliament if he was found to be a dual citizen.

The revelation created a fresh crisis for the embattled Turnbull government, only days after the High Court disqualified former deputy prime minister Barnaby Joyce and former Nationals deputy leader Fiona Nash, who inherited British citizenship by descent through her father.

It also came only two days after Senator Brandis assured the nation on that he had no reason to believe any further Coalition members held dual citizenship.

But Coalition colleague Eric Abetz and two legal experts have warned that Senator Parry may not be the last politician exposed as having dual citizenship.

“I would simply call on all of them [politicians] to do the right and honourable thing, and follow the principled lead of the President of the Senate,” Senator Abetz said on Tuesday.

Another Liberal MP, Andrew Laming, said he was “speechless”. “This from someone holding one of the highest positions in Parliament,” he said.

Meanwhile, University of Sydney constitutional law expert Anne Twomey told The New Daily that while the High Court’s decision had provided clarity, that “does not necessarily mean that all politicians have yet admitted the truth regarding their status”.

After last week’s High Court decision, the barrister who kicked off the citizenship crisis when he exposed the New Zealand citizenship of former senator Scott Ludlam, John Cameron, said the cases would not be the last.

Senate President Stephen Parry has reportedly revealed he’s a dual citizen. Photo: AAP

“There will be others,” Mr Cameron told AAP.

“This opens up a huge can of worms.”

Speaking after Senator Parry’s explosive admission, the Attorney-General hinted that section 44 (i), which prevents parliamentarians from holding dual citizenship, needed to be reformed to solve the crisis, saying it “sits oddly with the notion of a multicultural democracy”.

Senator Brandis said the law in its current form risked potentially disqualifying “millions of Australians from standing for Parliament”.

“Now, that is not a good thing,” he said. “So in one way or another, the issue does need to be dealt with.”

But he dismissed renewed calls for an audit of all parliamentarians’ eligibility as proposed by members of the crossbench and some constitutional law experts. That process could become a “witch hunt”, he said.

Despite the High Court’s ruling on Friday, University of New South Wales constitutional law expert Professor George Williams told The New Daily the current situation was untenable, saying he supported an audit of politicians’ eligibility.

“This uncertainty could continue for a number of months, and we need a process to resolve things in a better way,” he said.

“Quite apart from any audit, it is clear that section 44 is in need of amendment, lest these issues continue into future parliaments.”

Senator Parry, who was responsible for referring six senators to the High Court over citizenship eligibility questions, is the first Liberal politician to become implicated in the citizenship fiasco.

He said in a statement released on Tuesday he had waited for the High Court’s decision before coming forward, and that the ruling had provided “absolute clarity”.

Labor’s acting leader Tanya Plibersek said the government was “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.

Despite Senator Parry’s admission, the Attorney-General on Tuesday repeated his assertion that no other Coalition members held dual citizenship.

“I have no reason to believe that there is anyone else in this position,” he said on Tuesday afternoon.

“Nobody else has come forward, and I’ve not seen any evidence that any other member of Parliament has this problem.”