Coronavirus: Victoria to enter snap lockdown amid new mystery COVID-19 cases

The Australian state of Victoria will enter a snap lockdown on Thursday night in response to its latest COVID-19 cases.

It will be the state's sixth lockdown of the pandemic and it's been less than a week since the last lockdown ended.

Victorian Premier Dan Andrews said the lockdown will begin at 8pm on Thursday (local time) and will last for seven days.

Victoria recorded six community cases on Wednesday. Three of the cases are linked to known outbreaks while the others are under investigation. There are now 80 active cases in the state.

"We only get one chance to act fast, only one chance to make difficult decisions that are the right decision," Andrews says.

"The alternative is we let this run, it gets away from us, and our hospitals will be absolutely overwhelmed. Not just hundreds of patients, but thousands."

The lockdown means Victorians will only have five essential reasons people can leave the house. They are getting food and supplies, exercising for up to two hours, care or caregiving, authorised work or education if it can't be done from home, or to get vaccinated at the nearest possible location.

Face masks are also mandatory indoors, other than at home, and outdoors unless there's an exception.

Andrews says the lockdown begins at 8pm instead of midnight to avoid people going out and spreading the virus.

"This evening, go home and begin that lockdown. Don't be out and about because all you might be doing is spreading the virus," he says.

"I would prefer we didn't have to make this decision now. But my fear is if we were to wait a few days ... there is every chance [that] instead of being locked down for a week, this gets away from us."

He says while the lockdown is currently planned for seven days, he can't guarantee it'll end after this time.

Earlier on Thursday, Andrews said the priority was to "avoid what’s happening in Sydney".

"We've got to do everything we can to avoid cases getting out of control," he said.

"Everyone has been very clear about the fact there is only one real way to deal with Delta outbreaks."

When asked about a potential lockdown earlier on Thursday, Victorian Health Minister Martin Foley said he had "nothing to say", but would share any information that came to hand.

"We've always said that we will continue to assess outbreaks on a day by day basis and we know things can turn very quickly, we started yesterday with no cases ... it just goes to show that this pandemic is not over."