Labor has accused Riverina MP Michael McCormack of failing to provide sufficient evidence that he is not a dual citizen.

The fresh doubts were raised following the finalisation of the Federal Parliament's citizenship disclosure process this week. 

Labor’s legal affairs spokesman Mark Dreyfus identified Mr McCormack as one of nine MPs who have citizenship questions to answer. 

Mr Dreyfus told Fairfax Media it was a “matter of the constitution of Australia”. 

“I'm simply making the point that the High Court decisions need to be applied, the constitution needs to be observed,” Mr Dreyfus said. 

The High Court has said it is a matter of foreign law, foreign citizenship law," he said. 

Mr McCormack’s maternal grandfather was born in Greece, however, the Greek embassy does not have him registered on Greek municipal records, a requirement of being a citizen. 

The Riverina MP has since responded to Labor’s accusations and told the Cootamundra Herald he was “very sure” of his eligibility.

“I checked this out prior to gaining election in 2010 … and my paperwork is quite clear,” Mr McCormack said. 

“I have never sought out Greek citizenship.”

Mr McCormack said he had sought “written confirmation” which had been submitted to Parliament by the processing date, but remained proud of his Greek heritage. 

“Sure, I have a Greek grandfather ... but I am not a Greek myself,” he said. 

Labor has also accused Liberals Julia Banks, Alex Hawke, and Arthur Sinodinos of being Greek citizens after claiming evidence provided by the Greek embassy was “unconvincing”.

Under section 44 of the constitution, dual citizens are ineligible to sit in parliament.