The Victorian opposition has written to Police Commissioner Graham Ashton asking for a probe into whether Mr Languiller broke the law in claiming the allowance.

The letter calls for police to investigate whether Mr Languiller made false statements on his electoral enrolment documents or if he ever lived in Queenscliff.

Mr Languiller has repaid $37,800 he received from the allowance and admitted claiming it fell outside community expectations.

Shadow attorney-general John Pesutto's letter to police said Victorians had been infuriated by Mr Languiller's conduct.

"The question of whether that conduct breached any laws should, therefore, be investigated as a matter of urgency," he said.

The letter also questions why Mr Languiller has not disclosed travel, driver or second-residence statutory declarations or other documents to "address public concern" about the matter.

Mr Languiller has taken one month's leave while managing high blood pressure and depression. He did not return Fairfax Media's calls.

Mr Languiller's former deputy, Don Nardella, may also face a police investigation after the opposition wrote to Mr Ashton earlier this month calling for a probe of his second-residence claims.

A police spokesman confirmed that two matters had now been referred to police. He said one matter had already been allocated to an investigator for assessment and the second request, received on Thursday, would also be assessed by an investigator.

The Australian Electoral Commission has also written to the state opposition confirming officers from its integrity unit were discussing allegations concerning the electoral enrolments of Mr Languiller and Mr Nardella with the Victorian Electoral Commission.

"The outcome of the discussion will determine the AEC's future action in this matter," the letter said.

The second-residence allowance is meant for country MPs who must travel to Melbourne to fulfil their duties.

Both Mr Nardella and Mr Languiller chose the Bellarine Peninsula rather than their outer suburban electorates.

Mr Nardella has refused to repay almost $175,000 he claimed under the second-residence allowance for living outside of Melbourne while representing his Melton electorate.

A report by Parliament's auditor, PwC, revealed that Mr Nardella chose not to live in a St Kilda property because it was "not spacious enough".

Instead Mr Nardella had reportedly moved to a caravan park in 2014 that was owned by a family member so he could continue claiming the lucrative allowance.

The report said Mr Nardella paid $200 a fortnight for the caravan. He is now sitting on the crossbench after quitting the Labor Party after serving in Parliament since 1992.

The PwC report said that when Mr Nardella left his Ballarat home after the breakdown of his relationship in 2014 he should have taken the "simpler option" to live in his St Kilda property or move to his Melton electorate.

However, the report also said Mr Languiller had intended to move his home base to Queenscliff but spent little time there due to family circumstances.

Another report into all MPs who receive the second-residence allowance is due to be handed down soon.