Turnbull's plan to end citizenship chaos

Malcolm Turnbull said his plan to resolve the dual citizenship crisis could send more MPs to the High Court.

The prime minister is due to discuss the plan with Opposition Leader Bill Shorten on Wednesday, ahead of a Senate meeting next week.

Within 21 days of the parliament approving the measure, MPs will be required to provide to the registrar of members' interests a declaration that he or she was not, to the best of his or her knowledge and belief, a citizen of any country other than Australia.

They will also be required to declare the birthplace of their parents, but not their grandparents.

If they had been a dual citizen, MPs would need to provide details and evidence of the time and manner in which their foreign citizenship was renounced or otherwise came to an end.

Mr Turnbull said the disclosures could reveal a number of "line-ball cases" which end up in the High Court.

In some cases, members may choose to resign.

However, the prime minister has refused to call it an "audit" saying it puts the responsibility on each MP.

Mr Shorten said he would engage constructively with the prime minister.

But the Labor leader wants to ensure the process satisfies all Australians there are no remaining clouds over the eligibility of MPs to sit in parliament.

The Greens will still seek Labor and crossbench support next week for a special parliamentary committee to scrutinise all MPs, using the advice of expert citizenship lawyers.

It comes after Liberal MP John Alexander became the latest parliamentarian to be embroiled in the citizenship saga.

Fairfax Media reported on Monday the MP for Bennelong's father, Gilbert Alexander, was born in England in 1907 and arrived in Australia in 1911.

A search of British records found no trace of Gilbert Alexander, who died in 1987, having formally renounced his UK citizenship before his son was born in 1951.

The case resembles that of former Nationals deputy leader Fiona Nash, who was disqualified by the High Court over her British citizenship by descent through her father.

If disqualified from parliament, the government would be forced to a by-election in the Sydney seat which Mr Alexander holds by a 7.8 per cent margin.