The NSW government blindsided employer groups and Albury and Wodonga councils by announcing late on Sunday the only reason residents could travel across the border was for employment, health and education reasons with a redefined 2-kilometre border community zone also introduced.

The border closure was first introduced a fortnight ago with initial permits issued expiring and needing to be updated.

But the changes have been introduced without any fresh cases of coronavirus either side of the border since the initial closure was announced.

The Border Mail contacted Ms Berejiklian's office after the beefed-up border closure rules failed to rate a mention at her daily media conference in Sydney on Monday.

"The growing rates of community transmission in Victoria have us on high alert and the health advice clearly indicates we need to have stricter border closures in place, making it harder to get a permit and easier to cancel them," a NSW Government spokeswoman said.

"The NSW Chief Health Officer Dr Kerry Chant recommended the NSW government take this step because travellers returning or visiting from Victoria, in particular greater Melbourne and Mitchell Shire, pose a risk of increasing COVID-19 in NSW.

"The pandemic is not over and Victoria is seeing significant levels of community transmission in many areas of the state.

"Tightening restrictions on the borders will further protect the health of NSW citizens.

"We understand this will cause strain on border communities, but the government's priority is the health of eight million citizens of NSW.

"All NSW residents are strongly urged not to travel to Victoria."

"The measures will be in place for as long as the health advice recommends.

Australian Industry Group's North-East Victoria and Riverina manager Tim Farrah said his office was swamped with concerns following the latest announcement.

"What has changed since the initial border closure that makes them think that reducing the amount of travel between the border communities is going to stop the spread of the virus into NSW when there are no covid cases in these communities?" he said.

"The feedback from our members is they are very confused as to what is the problem the NSW government is trying to solve.

"If they are trying to stop coronavirus coming out of Melbourne how is restricting movement from people living on the Victorian border travelling into NSW going to help?

"There have been no more confirmed cases in North-East Victoria border towns since the border closure started."

Ms Berejiklian told Sydney reporters there were 20 new cases in the state overnight and each one was from a known source.

In Victoria, there were another 275 fresh cases, but none were in Murray River communities.

"We've got the ability here in NSW to keep moving forward while we are controlling the spread," Ms Berejiklian said.

"If we get through the next few weeks and next month we will have confidence we can keep moving forward in NSW.

"We are dealing with potential seeding from Victoria, we are dealing with the fact people were more mobile during the school holidays and we are dealing with the fact restrictions were considerably eased.

"Those three things make this a critical period."

NSW chief medical officer Kerry Chant and cross-border commissioner James McTavish addressed representatives from Albury and Wodonga councils late on Sunday about the changes.

Wodonga mayor Anna Speedie confirmed the two councils had no prior warning of the changes with VIctorian Premier Daniel Andrews late last week hoping he could sway his NSW counterpart to ease back the border closure.

"The justification is around the numbers in Melbourne and the fear of the (virus) being seeded (in the local community)," Cr Speedie said.

"But our community, like I've always said, has been really great at doing what it needs to do to keep it really safe.

"We had no indication this was going to take place. Our community, yet again, faces immense frustrations."

Prime Minister Scott Morrison backed the border closure measures being ramped up.

"This has been something that has been done co-operatively with Victoria," he said.

"I spoke to Premier Berejiklian at length this morning about a number of issues. And this was one of them.

"And I think what we have seen in NSW with the cases that have presented, is the government really getting on top of the contact tracing very quickly and the isolation."