Scott Morrison has thrown his support behind the Victorian government's tough suburban lockdowns designed to save Melbourne from coronavirus.
The prime minister has also warned people who refuse to be checked for the disease could face fines as a hotspot testing blitz continues.
Mr Morrison said there was nothing surprising about Melbourne's outbreak after .
"Where outbreaks do occur you need to move on them as the Victorian government is and they have our full support with that," he told the Nine Network on Wednesday.
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.
Victorian Premier Daniel Andrews has launched a judicial inquiry into hotel quarantine, with a slew of cases linked to staff infection control breaches.
Mr Morrison said mistakes in hotel quarantine were lessons for other states, noting no system was be perfect.
He said it was disappointing people in Melbourne were refusing to get tested.
"We're doing this in an Australian way. We're looking to do it through incentive, through the use of carrot, not stick," the prime minister said.
"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."
But Mr Andrews said Victorians will not be forced into taking tests in the lockdown areas because it would be logistically difficult and only possible if police accompanied testing staff door to door.
He said analysis of why tests were refused is still being done and includes families who denied permission for their children to be tested.
"The only people who can enforce and apply fines or other penalties are in fact members of Victoria Police and if I'm going to have every single person who's testing accompanied by a member of Victoria Police, then this is going to present a whole lot of very practical problems," Mr Andrews told ABC Melbourne radio on Wednesday.
"The key point here is all we can do is urge people to get tested."
He said increasing fines or threatening mandatory quarantine was also not practical.
"You can make all manner of threats, but they won't necessarily change anybody's behaviour. It may well be people simply don't answer the door," Mr Andrews said.
A COVID-19 testing facility in Melbourne. Source: AAP
'Masks may be part of the option'
Australia's Acting Chief Medical Officer Paul Kelly said Victorian health authorities were looking at whether to change health advice to recommend face masks in hotspots.
"If people are in that setting and cannot avoid large groups of people, masks may be part of the option. It's not the only solution," he told the ABC.
Under Victoria's aggressive coronavirus suppression measures, 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.
Mr Morrison downplayed criticism from Queensland Premier Annastacia Palaszczuk, who implored him to stop picking on her state over border closures.
"I think you can file that under a Queensland election (due on October 31)," he said.
Anthony Albanese said he wasn't surprised Ms Palaszczuk was frustrated with the prime minister for singling out her state while others remained closed.
"This needs to be based upon medical and health advice, not based upon politics," the federal opposition leader told reporters.
People in Australia must stay at least 1.5 metres away from others. Check your state’s restrictions on gathering limits.
Testing for coronavirus is now widely available across Australia. If you are experiencing cold or flu symptoms, arrange a test by calling your doctor or contact the Coronavirus Health Information Hotline on 1800 020 080.
The federal government's coronavirus tracing app COVIDSafe is available for download from your phone's app store.
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