Three Labor MPs and one crossbencher have resigned from Parliament over dual citizenship, setting up a Saturday byelection bonanza with voters to go to the polls in four states.

Labor MPs Josh Wilson (Fremantle, Western Australia), Susan Lamb (Longman, Queensland), Justine Keay (Braddon, Tasmania) and the South Australian Centre Alliance’s Mayo MP Rebekha Sharkie confirmed on Wednesday afternoon before Question Time they would re-contest their seats.

The resignations were sparked by the High Court’s ruling on Wednesday that Labor senator Katy Gallagher was also ineligible to stand at the 2016 election.

It means voters in four states will go to five byelections in the coming weeks following Labor MP Tim Hammond’s decision to resign for family reasons last week.

Wednesday’s events further shatter Opposition Leader Bill Shorten’s guarantee last year that no Labor MPs would be caught up in the citizenship crisis, after David Feeney’s downfall in January.

Mr Shorten did not apologise for the latest development, saying the High Court had created “a new precedent”, a claim fiercely rejected by the government.

He said the three Labor MPs had acted in good faith and was confident they would be eligible to contest the upcoming byelections.

At a media conference, Ms Sharkie confirmed she would stand again as a Centre Alliance (formerly Nick Xenophon Team) candidate, denying speculation she intended to switch to the Liberals.

“The High Court ruling in Gallagher, I believe, is quite clear,” she said.

“Consequently, I will resign from the Australian Parliament today and seek re-election at the forthcoming by-election, which I believe the earliest can be the 16th of June and I would hope it would be that date.”

Ms Sharkie would face a tough challenge in her seat of Mayo, which was a Liberal seat since 1984 before she won it under the Nick Xenophon Team banner in 2016.

Following her announcement, the three Labor MPs resigned in the House of Representatives.

Ms Lamb, whose electorate of Longman is held by Labor by less than 1 per cent, said she would recontest her seat because “Speaker, I am not done yet”.

“This is not a valedictory speech, let me be very clear,” she said.

I am putting the government on notice that, ultimately while this decision lays in the hands of the amazing people of Longman, I intend to be back.”

The Labor backbencher gave an emotional speech last year defending her dual citizenship, which she said could not renounce because she was estranged from her mother who held the documents needed.

Asked if Ms Lamb had retrieved the documents, Mr Shorten said: “I am not aware of each piece of paper that she has.”

Pauline Hanson all but confirmed One Nation would run a candidate in the seat, which attracted a 10 per cent One Nation vote in 2016.

Ms Keay, who holds Braddon by 2.2 per cent, would be expected to hold her seat in north-west Tasmania.

High-profile former Tasmanian senator Jaqcui Lambie confirmed she would not contest Braddon at a byelection, saying she was focused on returning to the Senate.

The five byelections are likely to be in June.

Attorney-General Christian Porter had demanded all four MPs resign after the High Court’s ruling on Wednesday.

The decision on Wednesday appeared to leave no room for those MPs to argue they were eligible under Section 44, with the court saying the case turned “upon “one issue” – whether Ms Gallagher was “irremediably prevented by foreign law” from renouncing her dual citizenship.

“An affirmative answer cannot be given merely because a decision might not be provided in time for a person’s nomination,” the court said.

Attorney-General Christian Porter accused Labor of talking “rubbish” by claiming the court had created a new precedent.

“It is a crystal clear clarification of the law as it was stated in the [Matt] Canavan decision last year, and anyone, Bill Shorten or anyone else, who says this is a reinterpretation or a change, is talking absolute rubbish,” he said.