Victoria is going hard to contain the unacceptably high spike in new cases of coronavirus, sending residents of 36 suburbs back into lockdown for a month.
Another 64 cases were uncovered in the state on Tuesday, bringing the number detected since a testing blitz began last Thursday to 233.
"That is an unacceptably high number and one that poses a real threat to all of us," Premier Daniel Andrews said.
Residents of 10 postcodes across Melbourne will be put under stay-at-home orders from midnight on Wednesday until July 29.
"Such is the nature of this virus, it is so wildly infectious that if we don't take these steps now we will finish up in a situation of rather than locking down 10 postcodes, we will be locking down every postcode," Mr Andrews said.
"I don't want to get to that point."
He acknowledged the move would be "deeply painful and damaging" for businesses in those areas.
A former judge will be appointed to investigate infection control breaches, including sharing cigarette lighters, after the outbreaks in Melbourne's north were genetically traced back to staff at hotels with international travellers in quarantine.
International flights will be diverted from Melbourne for two weeks.
Victoria ramped up testing over the past few days, conducting more than 17,400 tests on Monday alone, as officials tried to get a handle on the extent of the outbreaks.
But the premier said despite the publicity around the importance of finding infected people, nearly 1000 people in two of the hot spot suburbs had refused to be tested.
Another 800 federal public servants and clinical staff will join Defence personnel helping the Victorian efforts and Mr Andrews said he wouldn't hesitate to ask for extra help if needed.
The federal deputy chief medical officer likened the Victorian move to the April localised lockdown in northwestern Tasmania.
"The actions being taken by the Victorian government will save lives," Michael Kidd said.
South Australia has scrapped plans to reopen its borders on July 20 because of the Melbourne outbreak.
Premier Steven Marshall will instead pursue a travel deal with NSW and the ACT.
Queensland also announced it will reopen its borders on July 10 - as widely anticipated - but will continue to ban Victorians from entering the state.
NSW Premier Gladys Berejiklian is not considering closing the border but she has reiterated Victorians are not welcome to attend major events in the state until further notice.
Prime Minister Scott Morrison said it made little sense for any state to bar all Victorians.
"There is a hot spot in one part of Melbourne. Admittedly, it's very serious, it has our total focus and it is a great concern," he said.
"But if you're living in Wangaratta, then you're no more affected by what's going on in those suburbs of Melbourne than if you're living in Whyalla."
There were five new cases in NSW and two in WA on Monday, all of them overseas travellers in hotel quarantine.
Australian Associated Press