Nicola Roxon, the Australian health minister admitted that she once courted executives from tobacco firms for donations. But Noxon vowed that she would keep up her battle for plain cigarette packaging.
Roxon said inviting three Philip Morris executives to a fundraising dinner in 2005, a year after her Labor Party banned political donations from tobacco companies, was a "big mistake".
"The invitations were sent and that was wrong," she told Macquarie Radio.
Roxon, who was an opposition member of parliament at the time, said she had checked her records and none of the executives attended the dinner or made donations.
She said it was an embarrassing revelation as she pursues the government's plans to have all cigarettes are sold in bland, olive-green packaging and contain graphic health warnings in a bid to reduce smoking rates.
"Of course that's embarrassing, when I'm prosecuting what is a world first, in terms of introducing plain packaging for tobacco," she said.
"But clearly they (tobacco companies) are going to try and fight us in every way, that's fair enough, but our government's very determined to press ahead with that, and this won't change our determination."
Roxon, who has previously admitted accepting seats to the Australian Open tennis tournament from Philip Morris in 1999, said the revelations did not blunt her attack on the opposition for accepting donations from tobacco firms.
Australia already forces stores to hide cigarette packets for sale, and the plain packaging laws will be the strictest in the world.
Under the proposal, all logos will be removed from cigarette packaging from 2012 and tobacco companies must print their brand name in a specific font.
The plan has enraged the tobacco giants, who say it will reduce their profits and see counterfeit products flood the market because plain packaging is much easier to reproduce.
Seven powerful United States business groups, including the US Chamber of Commerce, added their objections Wednesday, saying the move could place Australia in breach of its international trade obligations.
But Roxon said the proposed legislation was not illegal and Australia was entitled to make laws to protect the health of its community.
"Ultimately, international organisations can have views, but we have to be the masters of our own destiny," she said.