Australia must not allow an expansionist China to subvert Australia's national interests, former US secretary of state Hillary Clinton warns.

Ms Clinton said Australia must stand up to "under the radar" efforts to influence Australian politics as China extends its influence and power.

The former US presidential candidate said Australia must be a strong and savvy advocate for its own interests and understand how best to deal with an expansionist China.

"I would hope that Australia would stand up against efforts, under the radar as we say, to influence Australian politics and policy," Ms Clinton told an event in Melbourne on Thursday night.

"You must not let that happen. It is insidious."

It could eat away at the fabric of democracy and build distrust, she added.

"If you think there's a hidden hand somewhere that is buying off politicians or otherwise exercising influence, then that begins to really tear at the fabric of a democratic society.

"It is imperative for the Australian government to protect Australia's interests."

Ms Clinton said the US must remain a Pacific power, having provided a counter-point to Chinese expansionism.

"I am hoping that we will have American leadership once again to back you up and support you in what you need to do to be a good trading partner, take advantage of the strategic position you find yourself in, but not allow China to undermine or subvert your own national interests or values."

Ms Clinton said Australia must pay heed to warnings about Chinese efforts to gain political power and manipulate policy outcomes.

"This is an urgent problem and one we must confront immediately and together."

Ms Clinton said what had been learned about the Russian interference in the 2016 US election, which she lost to Donald Trump, was more than alarming.

"It is a clear and present danger to democracy," she said.

Ms Clinton said information warfare was waged from within the Kremlin.

"The Russians are still playing on anything and everything they can to turn Americans against each other, from issues of race and gun violence to the humanitarian crisis in Syria.

"And it's not just happening in the United States.

"This is bigger than one candidate, one election or even one country."

Before being joined on stage by former Australian prime minister Julia Gillard, Ms Clinton also said the only way to get sexism out of politics was to get more women into politics.

The 5000 attendees paid between $195 and $495 for tickets to hear Ms Clinton speak.

She will address another function organised by business events group The Growth Faculty in Sydney on Friday night.