Victoria has recorded eight new cases of coronavirus since yesterday including five cases in the community and three cases in hotel quarantine.

Five of these cases were reported yesterday.

This brings the number of active cases in Victoria to 18 including nine locally acquired cases and nine in hotel quarantine.

All five of the cases in the community have been identified as primary close contacts to the existing cases in the Mentone and Mitcham clusters. This means that all active cases in the community have been linked to existing cases and the origin of these cases continues to be investigated.

Four of these cases are located in metropolitan Melbourne and one in regional Victoria in Leongatha.

The eight new cases include four males and four females. One person aged under 18, one person in their 30s, one person in their 40s, one person in their 50s, one person in their 60s and three people in their 70s.

UPDATE 11am

Two more Victorians with reported links to a bayside Thai restaurant have tested positive to coronavirus in NSW.

The duo left Victoria on December 30 and travelled to the south coast, visiting a hotel and cafe before getting tested in NSW, that state's chief health officer Kerry Chant said on Friday.

The two are back in Victoria now and understood to be among 170 close contacts of eight earlier locally transmitted cases, believed to be linked back to outbreaks in NSW.

It was not immediately clear when they were notified about being close contacts.

They are not yet officially counted in Victoria's community transmission case numbers, which remain at eight.Victorian testing manager Jeroen Weimar said all eight cases are connected, with links back to the Buffalo Smile Thai restaurant in Black Rock where three of the positive cases dined.

"We now have two separate groups of people who are unknown to each other who were adjacent with each other in the restaurant," he said.

EARLIER 9am

Victoria has recorded no new locally-transmitted COVID-19 cases, but 170 close contacts of patients are isolating as authorities say there will be more diagnoses.

One of eight positive cases identified in the past two days is in the states east, prompting warnings of possible transmission outside Melbourne.

Victorian testing manager Jeroen Weimar said all eight cases are connected, with links back to the Buffalo Smile Thai restaurant in Black Rock where three of the positive cases ate.

"We now have two separate groups of people who are unknown to each other who were adjacent with each other in the restaurant," he said.

A NSW returned traveller was also at that restaurant.

Health Minister Martin Foley said that was the primary line of investigation for the outbreak.

No link has been found between the eight cases and any other known infections and genomic testing underway to confirm if the traveller is the root of the outbreak.

Mr Weimar said 170 primary contacts of those eight cases are the major concern, and hundreds of secondary contacts are also being asked to get tested and self- isolate for 14 days.

"If your primary close contact connection turns out not to have been infectious you will be released from that investigation and you are free to go," he said.

One of the positive cases recently moved to a holiday rental at Leongatha in the state's east, widening the area of close contacts.

"Do not think this is just a Bayside suburbs, Mitcham issue. This is not only a Melbourne issue, this is a Victorian issue," he said.

There was an influx of people rushing to get tested late on Thursday, Mr Weimar said, with many testing stations staying open longer to get through the high numbers.

Five exposure sites are among those authorities are most concerned about, including the Thai restaurant.

Royal Brighton Yacht Club, Holy Family Parish Catholic Church in Doveton, the clubhouse bar at Woodlands Golf Club in Mordialloc and the Village Cinema at Century City in Glen Waverley are also areas of concern.

On the state's borders, motorists are facing lengthy queues to enter from NSW as a quarantine deadline looms.

In the state's west at Genoa, one motorist on Friday reported a wait of almost six hours as a line of hundreds of cars snaked through a checkpoint.

Growing coronavirus case numbers in NSW on Thursday prompted Victorian authorities to impose a hard border from midnight Friday. Anyone arriving after that time must spend a fortnight in quarantine.

Mr Weimar said anyone who is already in line for the border when the hard restriction border comes into force at 11.59pm on Friday will still be allowed to isolate at home.

But those who come after the deadline must quarantine in a hotel for 14 days.

On Thursday acting premier Jacinta Allan reintroduced the mandatory masks requirement for indoors and reduced the number of visitors allowed in Victorian homes down to 15 from 30.

Victorians can continue to return from Canberra with a permit, while more details will be announced for border communities and people who are travelling through NSW to return to Victoria.

EARLIER

Ballarat families returning home in the sudden COVID changes are among those facing lengthy queues to cross the NSW border into their home state, as a COVID-19 quarantine deadline looms.

In the state's west at Genoa, one motorist on Friday reported a wait of almost six hours as a line of hundreds of cars snaked through a checkpoint.

Authorities on Friday reported no new diagnoses of coronavirus for Victoria in past 24 hours, after the emergence of eight locally-acquired cases over the past two days.

Growing coronavirus case numbers in NSW on Thursday prompted Victorian authorities to impose a hard border from midnight Friday. Anyone arriving after that time must spend a fortnight in quarantine.

The news sparked an urgent dash for the border by many Victorians holidaying outside the state.

Anyone crossing back on Friday needs to have a border permit and must isolate at home for 14 days.

Those still making their way home have until 11.59pm Friday to cross before being forced into hotel quarantine as the state scrambles to avoid a third wave of the deadly virus.

Eight locally acquired cases of coronavirus were detected in 24 hours to Thursday afternoon, but Victoria is equipped to handle new clusters, Premier Daniel Andrews says.

The cases, which first emerged on Wednesday night, ended a 60-day streak without infections for Victoria.

All are directly or indirectly linked to the Smile Buffalo Thai restaurant in Black Rock on December 21, which was attended by a NSW returned traveller.

That traveller returned before border permits were in place and was being tested on Thursday.

It was also revealed on Friday that wastewater samples taken from Lakes Entrance on December 29 recorded traces of the virus, prompting calls or anyone in that area with symptoms to get tested.

The unexpected result means there will be an increase in samples taken from the Lakes Entrance area.

"We always knew there would be cases and clusters," Mr Andrews, currently on leave, posted on Facebook on Thursday.

"We have plans and systems in place to deal with precisely this scenario - and those are already well underway.

"I know this will be tough to take. Victorians have been through a lot this year and sacrificed so much.

"But we will get through it - together."

Victoria's testing chief Jeroen Weimar said early information indicated a potential exposure window between December 17 and 19.

Anyone who arrives back in Victoria from anywhere in NSW on Friday has to be tested and go into isolation for 14 days.

After that, returning Victorians will go into hotel quarantine.

Acting premier Jacinta Allan apologised for the border closure but said Victorians who are in NSW should not be surprised.

"We have been sending a very strong message for the better part of a week-and-a-half ... advising people to think very carefully about their travel to NSW," Ms Allan said on Thursday.

"These difficult decisions are about protecting the community."

Masks are also mandatory indoors and the number of visitors allowed in Victorian homes is down to 15 from 30, she said.

Victorians can continue to return from Canberra with a permit, while more details will be announced for border communities and people who are travelling through NSW to return to Victoria.

AAP