Victoria has recorded 57 new locally acquired cases of COVID-19 - the state's highest daily tally since the second wave of the pandemic.
The surge in infections comes as Victoria marks 200 days of lockdown in total during the pandemic.
Of the new local cases, the health department said 54 are linked to known outbreaks and 44 were in isolation during their infectious period. Three mystery cases are under investigation.
Premier Daniel Andrews said 41 of the 44 cases who were in quarantine during their infectious period tested positive on day 13 of their isolation.
As a result, many people will have to restart their isolation period again because of their positive test outcome.
"I know 57 seems like a very big number," he told reporters on Thursday.
"But when the vast majority of those have been in isolation for their infectious period, that's exactly what we want. That is the system working exactly as it should work."
Mr Andrews said many cases were Al-Taqwa College students and close contacts from the Islamic school outbreak.
Victoria’s COVID-19 commander Jeroen Weimar said the state is managing about 12,000 primary close contacts during the latest outbreak.
Mr Weimar said health officials were following up several leads to unravel the mystery cases. He said the three mystery infections identified were from Glenroy, Ascot Vale and Doncaster.
But Acting Chief Health Officer Ben Cowie has raised concern about three repeat waste water detections in Shepparton in the state’s north after regional Victoria exited lockdown.
“And I know the community in Shepparton has come out, and testing numbers have increased substantially over the last few days but we can do more,” Mr Cowie said.
A pop-up vaccine centre and testing site has been established in St Kilda where authorities have been focusing on a cluster of COVID-19 cases.
Meanwhile, Victoria Police says dozens of infringements have been issued in the past 24 hours, mostly for curfew breaches, illegal private gatherings and mask offences.
Police commissioner Shane Patton said four fines had been issued to attendees of the illegal engagement party held in Melbourne last weekend.
“We are now in the throes of arranging to engage with all of the other persons present and how we can conduct those interviews through Zoom and other areas to ensure that we have proper identification,” he said.
Commissioner Patton said the people involved with the party have been cooperative with police and the investigation was continuing.
Melbourne's stricter lockdown measures will last until at least 2 September after the government tightened the rules further on Monday to curb the spread of infections.
With AAP.
SBS is providing live translations of daily New South Wales and Victoria COVID-19 press conferences in various languages. .
