Acting Prime Minister Michael McCormack and Health Minister Greg Hunt have refused to publicly condemn Liberal MP Craig Kelly and the Nationals' George Christensen.

The conservative backbenchers have used Facebook to share conspiracy theories about controversial unproven coronavirus treatments.

The Australian Medical Association is calling on the federal government to launch an advertising campaign against health misinformation.

AMA president Omar Khorshid said people in positions of power could deliver online misinformation which others could easily absorb.

"We have seen this with the anti-vaccination movement and the countless conspiracy theories about the COVID-19 pandemic that circulate constantly on the internet," he said.

Labor has demanded senior cabinet figures condemn the coalition duo who are refusing to take a backward step.

Opposition health spokesman Chris Bowen said Mr Kelly had made a systemic and deliberate attempt to undermine medical health professionals.

"Craig Kelly is a menace and at every turn, Scott Morrison and now Michael McCormack, acting prime minister, have failed to call him out," he said.

Mr Kelly on Tuesday fired off a fresh barrage of posts championing Ivermectin, an unproven coronavirus treatment Facebook warned him over last week.

Health Minister Greg Hunt wouldn't be drawn on Mr Kelly's accusation health officials had engaged in child abuse for encouraging face mask use.

"There will be different views from different people," he said.

But Mr Hunt argued Australia's success in combating coronavirus stemmed from governments acting based on expert health recommendations.

"Our advice comes from what I believe are the best medical advisers in the world. That's what's protected Australia and that's what we're going to continue to do," he said.

"I would urge everyone to listen carefully to the advice of the Australian medical regulators and Australian government medical advisers."

Mr Christensen and Mr Kelly have shared material criticising masks and lockdowns, while also promoting hydroxychloroquine as a coronavirus treatment.

Mr McCormack told people railing against Mr Christensen's Facebook posts to "toughen up" and claimed "facts are sometimes contentious".

"You might look out there and say the sky is blue and I can see from here that it's grey. If we go out from this rotunda there are probably blue patches," the Nationals leader said in north Queensland.

"There are a lot of subjective things."

Australian Associated Press