Leading Labor figures are calling for confirmation Coalition MPs are eligible to sit in Parliament even though a number of their own MPs are refusing to provide documentary evidence they are not dual citizens. 

On Thursday, Labor frontbencher Jim Chalmers slammed the government's handling of senator Matt Canavan's dual-citizenship situation, saying Prime Minister Malcolm Turnbull needed to "come clean and say who else might be at risk". 

Senator Canavan resigned from cabinet on Tuesday, saying he had discovered his mother had signed him up for Italian citizenship when he was 25, without his knowledge. 

"I just think the country would like a bit of certainty," Mr Chalmers told Sky News. 

"If there are other Coalition MPs in the same boat, we should hear about it." 

Labor leader Bill Shorten has called for the Italian government, either directly or through Senator Canavan, to release all the documents relating to the former resources and northern Australia minister's case. 

"It would be good if they could release any documentation around this matter," Mr Shorten told ABC Radio in Melbourne on Wednesday. 

Of the 23 federal MPs who are born overseas, 10 are Labor MPs. Of those, only three - Anne Aly, Sam Dastyari and Josh Wilson - have provided documentary evidence that they have taken reasonable steps to renounce their dual citizenship. 

Several of the others, including frontbencher Penny Wong, have pointed to an ALP statement released last week, which notes the party is "confident that every member of the Labor caucus has been properly elected". 

Other Labor MPs who have not released documentary proof include Maria Vamvakinou, Tony Zappia, Doug Cameron, Alex Gallacher, Brendan O'Connor and Brian Mitchell. 

Mr Mitchell, the member for Lyons in Tasmania, has said he is happy to provide information to Parliament if it was requested. 

Some Labor sources have told Fairfax Media that MPs have been discouraged from releasing documentary evidence because it will open a "Pandora's Box", with the media and public then pressing for further personal details. 

However, other senior Labor sources have denied this, saying there has been no formal direction to members and it is a decision for individual MPs. Labor sources have also stressed the party has "very rigorous" processes for checking the eligibility of potential candidates. Ahead of the 2016 election, this included a legal team at both the state and national levels to iron out potential issues with citizenship. 

Other overseas-born MPs who have not provided documentary proof of their sole citizenship include former Liberal frontbencher Eric Abetz, One Nation senator Malcolm Roberts and Greens senator Nick McKim, who is waiting for confirmation from the British High Commission. 

Defence Minister Marise Payne has encouraged all parliamentarians with question marks over their status to provide proof. 

"I would have thought that making the position as clear as possible is the best way to go," she told Radio National on Wednesday. 

Senator Canavan is not resigning from Parliament because of initial legal advice that as his registration happened without his consent, he was not in breach of section 44 of the constitution. Senator Canavan is now preparing to take his case to the High Court. 

In a press conference in Rockhampton on Thursday, Senator Canavan said he would let relevant documents come out as part of the court process. 

Earlier this month, two Greens senators, Scott Ludlam and Larissa Waters, resigned from parliament because they discovered they were dual citizens. 

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