Malcolm Turnbull reportedly donated $1 million from his own pocket to the Liberal Party during the federal election.
The Australian reports unnamed sources as saying the prime minister made the "tightly kept secret" donation in the second half of the eight-week campaign and it is understood not to be tax-deductible.
The donation reportedly went to a general poll of funds to pay for television advertising, direct mail-outs and polling.
Labor frontbencher Anthony Albanese was envious.
"I wish we had someone who had a lazy $1 million sitting in the corner that could just plonk into the campaign," he told the Nine Network on Friday.
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Liberal frontbencher Kelly O'Dwyer insisted she had no idea about who had contributed to the campaign but said the bigger concern was members of unions being forced to contribute to Labor campaigns.
Mr Albanese hit back, insisting shareholders of companies that pay thousands of dollars at fundraisers in Ms O'Dwyer's Higgins electorate had no say in how that money was spent.
Finance Minister Mathias Cormann was wary about the accuracy of the report but said all would be revealed eventually through the usual process of disclosure for donations.
"These sorts of things will be reported if indeed that has actually happened," he told Sky News.
Liberal party federal director Tony Nutt said donations were disclosed in accordance with legal requirements.
He also rejected a claim in the report that the party was "either in debt or broke", insisting the reporter did not put it to the party before publication.
The party's finances were soundly managed by federal treasurer Andrew Burnes, he said.
