Australia's coronavirus infection rate shows sustained slowdown

To ensure compliance, state authorities enacted sweeping powers to impose hefty fines and potential jail terms for anybody breaching rules that include a ban on public meetings of more than just two people.

Health Minister Greg Hunt reported there were about 4,400 coronavirus cases nationally, with the rate of growth in new infections slowing from 25-30% a week ago to an average of 9% over the past three days.

Of those, 50 people were in intensive care and 20 were on ventilators, Hunt said. The death toll stood at 19.

Based on the completion of more than 230,000 tests, the death rate for Australian cases was below 1%, significantly under the 10% being reported by some other countries and suggesting "early promising signs of the curve flattening," Hunt said.

"By having what we believe is the broadest and widest testing program in the world ... at this stage our numbers indicate that we are at the global forefront, we have a good picture of where we're at," Hunt said in a televised media conference.

"In these most difficult of times, with these most difficult of measures, that none of us had ever dreamt we would ever be involved in, you have risen to the occasion," he said. "To those Australians who are at home, to those Australians who are isolating or in quarantine, I want to say thank you."

Still, Hunt stressed that it was too early for Australians to breathe a sigh of relief and the new social distancing measures were crucial.

State officials had earlier warned that the slowing infection rate might have have more to do with fluctuations in testing numbers, given there was less access to doctors over the weekend.

"What we need to consider is the community-to-community transmission that we might not even know about," New South Wales (NSW) state Premier Gladys Berejiklian said in Sydney.

Public health orders enacted on Tuesday vary from state to state but generally include penalties of some kind for people flouting rules that include restricting public gatherings to just two people and the closure of outside gyms and parks.

People will still be able to leave their homes for valid reasons such as to visit a doctor, buy food and exercise while adhering to the social distancing rules.

NSW, the country's most populous state, is responsible for a little under half of the national infections and most of the death toll of 19. It introduced fines of up to A$11,000 ($6,779) in NSW and the potential of a six-month prison term for anybody found breaching the rules.

In Western Australia state, people who ignore self-isolating orders could be fitted with an electronic tracking device.

Authorities said on Tuesday they wanted to increase testing, especially in places of COVID-19 clusters such as Sydney's Bondi area, which drew attention earlier this month after people ignored social distancing rules and flocked to the beach.

Like all affected countries, Australia's financial and jobs markets have been roiled by COVID-19, prompting the government to unveil several stimulus packages.

Prime Minister Scott Morrison said in a tweet on Tuesday that 113,000 businesses had registered interest in a new A$130 billion ($80 billion) six-month wage subsidy.