NSW Labor leader Michael Daley denies he acted improperly while he was a Sydney councillor, amid claims he failed to disclose donations from developers when assessing development applications.
Mr Daley reportedly did not declare an interest in at least three cases during his time at Randwick City Council between 1995 and 2008.
They included applications by former Labor president Michael Williamson and the Randwick Labor Club, according to News Corp Australia.
However the opposition leader on Monday rejected any suggestion that he acted improperly when he was a councillor.
"In my 23 years in public life, I have always acted with integrity and propriety," he said in a statement.
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"As a Randwick councillor, I moved to strengthen rules regarding assessment of development applications, more than a decade before it became law in NSW. I was opposed by the Liberals."
Despite his denial NSW Premier Gladys Berejiklian said Mr Daley had some "serious questions" to answer, with the state election less than four weeks away.
"People who aspire to hold high office in public life need to answer questions and I call on the leader of the opposition to do that today," she told reporters.
"The leader of the opposition needs to answer whether he did or didn't or why he did or didn't respect the guidelines that exist."
Treasurer Dominic Perrottet indicated he won't be referring the matter to the NSW Electoral Commission but said the allegations go to Mr Daley's character and integrity as the aspiring premier.
"I think the public demand answers and if you can't run Randwick Council you can't run NSW," he said, speaking at the same press conference on Monday.
Mr Perrottet denied media outlets were tipped off by the Liberal Party.
Meanwhile, the NSW Nationals have declared water security the key issue in its election pitch ahead of the March 23 poll.
Deputy Premier John Barilaro, in launching his party's campaign on Sunday, said the government will invest $25 million to research the merits of the Bradfield scheme - a decades-old multi-state inland irrigation plan that would funnel water from Queensland, through NSW and into South Australia.
