There were 94 new cases of COVID-19 recorded in Australia on Sunday.

Of these, 74 were in Victoria, 14 in New South Wales and the remaining six in Western Australia.

All of the cases in NSW and WA were returned overseas travellers in hotel quarantine.

"The six new cases, four women and two men aged between 40-64, were all passengers on a flight from Dubai which arrived in Perth on 1 July and returned positive test results following WA Health screening conducted on day two after their arrival," WA Health said on Sunday.

"All the new cases are returning Western Australians from the metropolitan area."

The health department is interviewing all passengers on the flight, who are also in hotel quarantine, "to ascertain if there were any close contacts to the newly diagnosed cases onboard".

According to the federal health department, there were 45,399 COVID-19 tests conducted in the 24 hours to 9pm on Sunday.

Of the more than 8200 coronavirus cases, 11.2 per cent are considered "locally acquired – contact not identified" and 1.7 per cent remain under investigation.

Victorian Premier Daniel Andrews said 53 of the state's 74 new cases are under investigation.

Of the others reported, 16 are linked to outbreaks, four identified through routine testing and one new case detected in a returned traveller in hotel quarantine.

The state has locked down nine public housing towers in Melbourne for at least five days while stay at home orders apply in a number of postcodes.

Residents in nine public housing towers in Melbourne who were told they would have to stay home for at least five days have received "detention directions" with an end date of July 18. 

There are 13 cases linked to North Melbourne and 14 linked to Flemington, home to about 3000 people in total. 

“The nine towers involved (five in North Melbourne and four in Flemington) are now closed and residents are required to stay in their homes at all times,” the Department of Health and Human Services states.

“This will be in place for at least five days to ensure we can test every single resident. The lifting of this restriction will be determined by our success in testing and tracking this virus.”

According to the detention directions provided to residents on the weekend, the rules “apply beginning at 3.30pm on 4 July 2020 and ending at 3.30pm on 18 July 2020”.

“Your detention will be reviewed at least once every 24 hours for the period that you are in detention, in order to determine whether your detention continues to be reasonably necessary to eliminate or reduce a serious risk to public health,” the documents state.