Labor leader Bill Shorten insists his party has no financial interest in a software company providing a database of voters.
But he's now demanding Prime Minister Malcolm Turnbull answer whether he's used taxpayer allowances to fund the Liberal-owned firm Parakeelia.
The Liberal party has offered to cooperate with any inquiry after Labor sought an investigation from the auditor-general into the the flow of funds from the software firm.
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Mr Shorten has accused the Liberals of using Parakeelia to pay itself with taxpayer-funded allowances.
"Mr Turnbull needs to answer the question, is it improper? Has he paid his own taxpayer allowances into this company?" he told reporters in Adelaide on Thursday.
However, Mr Shorten faced scrutiny over his own party's use of the software firm Magenta Linas, whose clients also include unions, the WA government and BHP Billiton.
The Labor leader insists it's not the same arrangement.
"The Labor party has no financial interest in the ownership of Magenta Linas."
Asked whether he could rule out if money had been given to the ALP as a donation, Mr Shorten said: "I don't believe it has".
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The Australian Electoral Commission financial disclosures show Labor receipted Magenta Linas for $13,301 in "non-financial" and $1018 in "other" contributions in 2014/15.
Treasurer Scott Morrison said there was not a shred of any credible evidence to suggest any inappropriateness with Parakeelia.
He dismissed Labor's pursuit as a distraction from its "weak" economic agenda, adding the party had until 2014 been making payments directly to the ALP using taxpayer funds.
"This is just a desperate witch-hunt from the Labor party."
Parakeelia provides voter monitoring software to coalition MPs, for which they pay $2500 a year, either from their own pockets or from a taxpayer-funded allowance for software.
It is the Liberal party's second biggest donor, providing more than $1 million over the past three years.
