Melbourne's coronavirus hotspots are preparing for another month in lockdown as community spread of the virus increases.
Victorian health authorities confirmed 73 new coronavirus cases on Wednesday, which marks more than two weeks of double-digit increases.
Australia's Acting Chief Medical Officer Paul Kelly says face masks could be an option for people in hotspots to prevent the virus spreading.
"The Victorian authorities will come through with some guidance on that in the coming days," he told reporters in Canberra.
There were 87 new cases across the country on Wednesday, taking the total to 7920.
After an adjustment in reporting methods, there are fewer than 400 active cases in Australia, down from 693 on Tuesday, including 18 people in hospital.
Three people are in intensive care.
Professor Kelly said Australia had reached a milestone of 2.5 million tests, including 50,000 on Tuesday.
It comes as NSW announced people from the affected Melbourne areas face six months in jail or fines of up to $11,000 if they try to cross the border.
Victorian Premier Daniel Andrews said the new cases were mainly in the hotspot suburbs.
"We are finding new cases but there is the beginnings of some consistency here," he told reporters.
"That is obviously better than other options where we might see doubling and doubling again."
Prime Minister Scott Morrison warned people refusing tests could face fines.
"We're doing this in an Australian way. We're looking to do it through incentive, through the use of carrot, not stick," he told the Nine Network.
"But occasionally the stick will have to be put about, whether it's fines or other sanctions that are in place to ensure that we keep everybody safe."
He backed the Victorian government's drastic measures to curb the disease's spread.
"Where outbreaks do occur you need to move on them as the Victorian government is and they have our full support with that."
Lockdown will be reinforced across 10 Melbourne postcodes from Thursday until July 29.
People living in those areas will only be allowed to leave home for work, study, essential shopping, exercise or to receive or give care.
Victoria has launched a judicial inquiry into hotel quarantine, with a slew of cases linked to staff infection control breaches.
International flights will be diverted away from Melbourne for two weeks.
Queensland is banning Victorians from entering the state but welcoming other visitors from July 10.
South Australia has shelved plans to reopen its Victorian border but is weighing up a travel deal with NSW and the ACT.
Western Australia has announced an additional $36 million for elective surgery to tackle the backlog created when public hospitals were freed up for the virus.
Australian Associated Press