Doctors and the Greens have called out Labor on its Medicare scare campaign as the opposition continues its attack on the government.

Labor has used the burden of healthcare costs on family budgets to bolster its Medicare scare campaign against the Turnbull government.

The move comes as the opposition comes under fire from doctors and the Greens for over-reaching on claims the coalition has a secret plan to privatise Medicare.

Labor was implacably opposed to the overt or covert privatisation of Medicare, Opposition Leader Bill Shorten said on Wednesday.

Privatisation occurred when you increased the proportion of health payments made by individuals as opposed to the government.

"Put another way, Labor is against the increasing cost of health care being put on family budgets," he told reporters.

Greens leader Richard Di Natale says Labor should just stick to the truth because funding cuts to public hospitals and an extended freeze on Medicare rebates are scary enough.

"Of course Labor doesn't want to go there because they themselves cut hospital funding and froze the rebate, so instead they have chosen to link privatisation and Medicare," said.

The Australian Medical Association says outsourcing Medicare payments would in no way amount to privatisation.

"The current system is old and many elements of it date well back to the early 1980s," president Michael Gannon said.

"They're antiquated, they're rusty and the system needs substantial investment."

A move to change the payments system would not involve the privatisation of the whole show, Dr Gannon said.

Prime Minister Malcolm Turnbull agreed the payment system clearly needed to be upgraded.

"I don't think anyone argues about that," he told reporters in Cairns, adding his commitment was for any upgrade to be done within government, "full stop".

Mr Shorten said Labor had always been prepared to modernise the payments system.

"What we are not prepared to do is outsource the payments system to a large bank, to a foreign multinational," he said.

That was the "thin edge of the wedge of the dismantling of the Medicare system as we know it".