Melbourne's lockdown will be extended by at least another week as Victoria records another 20 locally acquired coronavirus infections, including another five mystery cases.
Fifteen of the new cases are linked to known outbreaks and 14 were in quarantine during their infectious periods.
But with the origins of the initial outbreak from last week still a mystery and the five new mystery cases on Wednesday, there was no option but to extend the sixth lockdown, Premier Daniel Andrews said.
"Sadly, today the cabinet of the government have met and we have determined to accept the advice of the chief health officer to extend for a further period of seven days, until 11.59pm next Thursday," Mr Andrews told reporters.
"This is very challenging, I know, for every single Victorian who would like to be going about their business, they would like to be open and have a degree of freedom that is simply not possible because of this Delta variant."
Permits for Victoria-NSW border residents
People who live on the Victoria-NSW border will now need a permit to travel between states.
Mr Andrews says residents of the cross-border community local government areas will need to obtain a permit to state-hop from 6pm on Friday.
He said the permit system would track who was entering Victoria from NSW and make it easier to rapidly get information to contact tracers and to monitor for compliance.
"It is not good enough to limit movement. We need to know who is moving," Mr Andrews told reporters on Wednesday.
"If this virus can get from Sydney to Byron Bay, to Armidale, then only a fool would think it couldn't get to Albury. It absolutely can. We need to go beyond a bubble. We need to have permits."
Mr Andrews says if the virus gets into the southern NSW communities, there is "every chance" it will spread into Victoria.
The state government says it is to better track who is entering Victoria from NSW and make it easier to rapidly get information to contact tracers and to monitor for compliance.
Health staff at a COVID-19 vaccination site at the Royal Exhibition Building in Melbourne, Tuesday, 10 August, 2021. Source: AAP
Spread of the virus in Caroline Springs remains the main concern for authorities. A healthcare worker who worked at the eye clinic at the Royal Children's Hospital is among those infected in this outbreak.
There are now 100 cases linked to the new outbreak and 13,800 close contacts are isolating.
Chief Health Officer Brett Sutton said he wanted border communities to be able to "go about their business safely".
"We want to reduce the risk and we want to be able to respond appropriately should any incursion into the border communities occur," he said.
The permit system will apply for the next 14 days and replace the licence checks currently in place.
Residents of the border towns can travel between states for for six reasons including medical care, compassionate purposes, work, education, playing sport or getting vaccinated.
