Victoria has recorded 288 new coronavirus cases, the nation's biggest daily increase since the pandemic began.
Premier Daniel Andrews confirmed the new cases today, with just 26 linked to known infections, while 262 remain under investigation.
The new cases push the state's active case tally past 1000 for the first time.
Previously, the highest daily state total in Australia was 212 cases recorded in NSW on 27 March.
Mr Andrews said the state's number of cases was "always going to get worse before it gets better".
"I know there will be great concern about these numbers. People will feel deeply concerned to see that number as high as it is," he said.
He said he was comforted by the record number of tests conducted in the state, including a record 37,588 tests yesterday.
Victoria's Chief Health Officer has requested people in locked-down metropolitan Melbourne and Mitchell Shire wear masks when they are out of their home and can't social distance.
Two million reusable masks and one million single-use masks will be distributed by the government
It comes as International flights arriving in Australia will be halved to ease the pressure on hotel quarantine systems around the country.
Australians returning home will also be made to pay for mandatory two-week stays in hotel quarantine.
Prime Minister Scott Morrison announced the changes after a national cabinet meeting with state and territory leaders today.
The reduction of flight arrivals from Monday will mean more than 4000 fewer people every week will return home.
All states will soon charge people for their two weeks in hotel quarantine.
"Where possible, we will seek to have some sort of national uniformity across those pricings," Mr Morrison told reporters in Canberra today.
Former health department secretary Jane Halton will lead a review of hotel quarantine after breaches in Victoria's system fanned infection rates.