Health authorities concede Victoria's coronavirus outbreak is likely to get worse before it gets better, after the state recorded another 75 new cases.
Prime Minister Scott Morrison says the entire nation will do everything it can to help contain the outbreaks.
He will canvass the possibility of local area lockdowns with Victorian Premier Daniel Andrews on Monday.
Victoria recorded 75 fresh COVID-19 cases on Monday, taking its tally to 367 new cases in a fortnight.
By contrast, there were seven new cases in NSW on Monday, three in South Australia and none in the rest of the country.
Victoria's chief health officer said it was a concerning increase.
"I think it will get worse before it gets better," Brett Sutton told reporters.
"It is very hard to make reductions in this space. What I would say is that we know what works already. We just need people to do it."
He said the new cases would have been infected almost a week ago, before an intense communications and testing campaign began.
Chief Nursing Officer Alison McMillan said the outbreak didn't amount to a second wave because there wasn't widespread community transmission around the country.
Nevertheless, it was vital to get on top of it as soon as possible.
"If you are sick - any symptoms whatsoever of a cold or flu, or the loss of taste or smell - please do get tested, testing is available broadly across the country and is free, you do not need a Medicare card," she told reporters in Canberra.
Mr Morrison is speaking with Mr Andrews about what further resources the state might need, potentially including support to lock down hotspot suburbs.
"The premier and I are very adamant that we do what is necessary to contain this outbreak," the prime minister told reporters in Sydney.
"Victoria will lead that approach and they will be the final arbiter of what steps they take, but we can leave no stone unturned and no resource left unapplied to this task."
The state has also moved to ensure people in mandatory hotel quarantine are tested for the virus after it emerged three in 10 people were refusing tests - a much higher rate than in other jurisdictions.
Those who refuse tests will have to spend an extra 10 days in quarantine.
A new saliva test developed by the Doherty Institute is being trialled in the state, but experts say at this stage it misses positive results in about 13 per cent of cases.
Deputy Chief Medical Officer Nick Coatsworth said medical officials were considering whether to recommend people in Melbourne wear masks when out in public.
Australian Associated Press