Testing of COVID-19 cases in Melbourne shows some are not linked to the original outbreak that triggered the state's most recent lockdown, the chief health officer has revealed.
Professor Brett Sutton told reporters genomic testing showed some people were infected with a different variant of the virus.
It is known as the Delta variant, Professor Sutton said, and is the predominant strain found in India.
"It's obviously a concern that it's not linked," Professor Sutton said.
More coronavirus news:
Professor Sutton said the family linked to the Delta variant had travelled to Jervis Bay in NSW. There were seven people linked to this cluster.
The variant had not been detected in the community anywhere in Australia previously.
He said officials were now trying to pinpoint who was the first person infected and it was possible the variant originated in NSW.
There were four new locally acquired coronavirus cases in Victoria overnight as restrictions eased across regional Victoria.
The results were detected among 49,439 test results received in the 24 hours to Friday morning.
More than 24,169 people received a COVID-19 vaccine dose.
There were two cases recorded in hotel quarantine on Thursday as the overall number of active cases across the state rose to 72.
Late Thursday, two suspected "fleeting" transmission cases of coronavirus used to justify Melbourne's lockdown extension were declared false positives.
Health authorities initially thought a woman caught COVID-19 at a Metricon display home at Mickleham, and believed a man similarly picked up the virus at Brighton Beach Hotel.
That was not the case, with an expert panel review confirming neither was infected.
The COVID-free pair and their primary close contacts will be released from isolation and any associated exposure sites stood down, including all in Anglesea along the Great Ocean Road.
Under eased restrictions for regional Victoria, there will be no limit on how far people can travel and outdoor gatherings of up to 10 will be allowed.
Masks will remain compulsory indoors and outdoors when social distancing isn't possible.
Schools, retail and hospitality will also be able to reopen.
Service Victoria QR code check-ins have become mandatory statewide in retail settings such as supermarkets, with businesses required to manually log the visits of people who do not have mobile phones.
Melbourne's lockdown, meanwhile has been extended until 11.59pm on June 10.
- with AAP
We have removed our paywall from this story about the coronavirus. This is a rapidly changing situation and we want to make sure our readers are as informed as possible. If you would like to support our journalists, subscribe here.
Our journalists work hard to provide local, up-to-date news to the community. This is how you can access our trusted content: