Mr Foley said the current roving border patrol was highly efficient, but if police needed more resources to set up more checkpoints they would.

"VicPol's operational advice is based on learnings from 2020 and learnings brought across earlier this year that a highly-mobile, unpredictable, technology-driven arrangements.... have been more effective," he said.

Mr Foley said the current system secured the border while not taking away from residents who live on the border.

Mr Foley said police were detecting an increasing number of people trying to breach the Chief Health Officer's order, more than they did under previous border closure arrangements.

He said a request by Victoria Police for ADF assistance with the closure, was denied.

Zero cases of COVID have been recorded in the community or in hotel quarantine.

He said late last night NSW advised a confirmed case from Greater Sydney was infectious while visiting Victoria and South Australia on July 8 and 9.

The case will be reported in today's NSW numbers.

He said the person was a removalist and visited households in Victoria. They stayed overnight in Victoria on the night of the 8th and drove to South Australia before returning to NSW and being tested on the 10th.

Mr Foley said details would come but it was possible the person travelled along the Hume Highway.

"We would expect there will be exposure sites [in Victoria] and we would expect there will be people required to quarantine as a direct response to that," Mr Foley said.

The Health Minister said they would be looking at his permit status, but many workers were eligible to cross the border.

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He said Victoria's closeness to NSW made the risk of incursions like this very high.

Mr Foley said there had been no regional cases during the current outbreak but given the lack of a ring of steel between Sydney and the regions, Victoria's public health team was sufficiently concerned to close the border.

He said the removalist was the third incursion during this outbreak wherein a positive case from NSW has entered Victoria.

Mr Foley said given the deteriorating situation in NSW and the incursion Victoria had to take the tough step to turn all of NSW red.

"Victoria needed to take the steps to seriously limit the movement of people and therefore limit the risk of incursions into Victoria," he said.

Mr Foley said the border bubble was in place and eligible people could cross with just their licence and continue to go about their business as usual.

"You can't go from those border bubbles into a red zone and expect to cross into Victoria, and you certainly can't have been to any exposure sites and attempt to cross to Victoria," he said.

Mr Foley said the decision was not made lightly and they are aware it will create inconvenience for some.

"The situation from NSW needs to be kept far away from Victoria," he said, noting the state has not had a case for 12 days.