More troops prepare to head to Adelaide for virus battle

Federal authorities are keeping a close eye on Adelaide's coronavirus cluster, with more troops preparing to travel to South Australia.

The coronavirus cluster in the city's north has grown to 20, with investigations continuing on another case.

There have been 11,000 tests conducted in the state over the past two days.

Federal Health Minister Greg Hunt has praised South Australians for getting tested, encouraging people without symptoms to also be checked for coronavirus.

"We are looking for each and every person who might have in any way, shape or form been exposed to come forward," he told reporters in Canberra on Tuesday.

Mr Hunt said there were 100 Australian Defence Force troops on the ground in South Australia, with authorities meeting to map out how much extra support was needed.

They will be deployed immediately after decisions are made.

Mr Hunt said states had been advised by the national panel of medical experts to increase screening for arrivals from Adelaide.

"Other states may choose to go further, but they'll have to explain that," he said.

But Queensland, the Northern Territory, Tasmania and WA have slammed the gates shut on South Australia.

NSW and Victoria - which has now gone 18 days without new coronavirus infections or deaths - have increased screening for Adelaide arrivals.

The measures could set off another round of clashes between the Morrison government and the states, after senior federal politicians criticised Victoria's approach to easing its tough restrictions.

Treasurer Josh Frydenberg was scathing about the impact lockdown had on the mental health of Melburnians.

Western Australia Premier Mark McGowan offered a frank assessment.

"Some of those ministers, Mr Frydenberg and some of those characters, their behaviour was appalling," he said.

"(Victorian Premier) Dan Andrews did what he had to do ... the fact they undermined, criticised and attacked the whole way along during a period of extreme pressure was appalling.

"Steven Marshall has done the right thing and I support him in what he's doing. I'd urge everyone to support him in what he's doing."