Border bubble permit applications commence on Thursday afternoon

His comments come as a permit application system required by border bubble residents to travel between the two states goes live this afternoon ahead of its enforcement from 6pm on Friday.

"It is a relatively simple online process," he said.

"I know it is so challenging for border communities with the risks we see and the increasing number of cases we are seeing in regional NSW.

"But it is so important that we continue to manage that border permit system and have a good sense of who is coming across the border."

The return to permits comes as two women from Sydney flew into Melbourne on Monday and didn't have correct permit to enter Victoria.

Mr Weimar said were intercepted by authorities and taken straight to hotel quarantine and have since been fined.

They have also tested positive to COVID-19.

"This is the risk of interstate travel at this point in time," he said.

"This is why the chief health officer has declared Sydney and NSW as an extreme red zone.

"This is why we are putting such significant barriers in place to stop all unnecessary travel between our states at this most critical time."

EARLIER: The Thursday update for new locally acquired cases of coronavirus is in for Victoria.

The Department of Health and Human Services said 21 cases had been reported in the 24 hours to midnight Wednesday: 17 have been linked to the current outbreak, with four still under investigation.

Of the new cases, 15 have been in quarantine throughout their infectious periods.

There are currently 137 active cases in Victoria.

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