Victoria will keep its border with New South Wales open and it will stick with its permit system for those coming in from the state.

Health Minister Martin Foley has again warned people not to travel into Sydney, saying there was “a significant risk that COVID-19 has seeded across the greater Sydney area”.

“If that is the case, and I stress that is an if, then we will have no choice but to declare all of Sydney a red zone,” he said on Saturday.

“That will mean anyone who has been in Sydney will not be allowed into Victoria.”

Anyone who does travel to Sydney could be stuck there, Mr Foley said.

He also said people coming from Sydney’s red zones would be spending Christmas in hotel quarantine.

“That is not a position we want anyone to be in,” he said.

At least one family will be, after two unaccompanied minors from the red zone flew into Melbourne Airport this morning.

They have gone into hotel quarantine with their carer, who had been self-isolating.

Travellers in Melbourne Airport are closely watching Sydney’s North Shore coronavirus outbreak. Photo: ABC News/Margaret Paul

Mr Foley said authorities were looking into how the minors had managed to board the plane.

“We are working with Melbourne Airport and the airline so as to establish how that happened,” he said.

“That clearly speaks to some issues at the Sydney end of things. We are going to follow that one through to make sure that doesn’t occur again.”

Permits required but not masks, yet

Sydney’s Northern Beaches will be locked down until Wednesday after NSW Premier Gladys Berejiklian confirmed 23 new COVID-19 cases.

She said 21 have been directly linked to the Northern Beaches outbreak, while two others were being investigated.

The Avalon cluster has grown to 38 cases.

As the cluster continues to grow, Victoria has effectively shut the border to people from those affected areas.

Tweet from @VicGovDHHS

A “traffic light” permit system was put in place beginning Friday night for anyone entering Victoria from NSW.

The permits are available through the Services Victoria website.

Everyone coming into the state from NSW, even if they are just passing through or are from a green zone, needs to apply for a permit.

The permits have only been available since midnight, but already about 52,000 have been issued.

Chief Health Officer Brett Sutton on Friday said given the 14-day incubation period for the virus, the permit system would be in place for a fortnight “at a minimum”.

The government is keeping a close eye on things in Sydney and Mr Foley said developments over the next 24–48 hours were critical.

If numbers stabilise, but then later “go awry” and begin rising, the government would consider extending the red zone, he said.

On Saturday, Mr Sutton said he was not yet considering implementing further precautionary measures, like wearing masks.

“Not at this stage. We will consider it as we need to,” he said.

“The focus is on where the risk is, which is in Sydney, in the Northern Beaches area.

“If there were anything to consider because we think that risk has been imported to Victoria, yes, we would review that.”

No new local cases

Meanwhile, the Victorian Department of Health and Human Services said no new locally transmitted cases of coronavirus had been discovered in Victoria.

“Everyone has sacrificed so much over the course of 2020, that is in our interests to make sure that that COVID-safe status, 50 days of hard earned COVID-free environment in this state is maintained,” Mr Foley said.

Two new cases tested positive in hotel quarantine.

“One of these cases was diagnosed as a member of an international flight crew who was quarantining in a hotel at the time of her diagnosis,” Mr Foley said.

“That crew member arrived in Australia on a crew-only flight with no passengers.”

That increased the number of internationally acquired cases to 10.

Acting Chief Medical Officer Paul Kelly has backed the plan in use by most states, to determine hot spot areas, rather than have to close borders totally.

“For the first time, the northern beaches of Sydney were declared a hot spot yesterday in anticipation for the extra cases that have occurred overnight,” he said on Saturday.

“I very much welcome the other states that are using that type of approach, so limiting it to where the problem is.”

“I would hope they will make that a proportionate thing as we have a lead-up to Christmas.”

-ABC