Two recent COVID-19 cases have been linked to a pub in southwest Sydney, with the venue temporarily closed and authorities searching for a third person who could have spread the infection.
Health Minister Brad Hazzard says a man in his 50s had been at the Crossroads Hotel in Casula on July 3, the same night as an earlier case.
"Now, obviously, that has major ramifications because that appears to be ... a likely point of connection where the two people could have actually come into some contact at least with the virus," Mr Hazzard said on Friday.
Anyone who attended Crossroads Hotel last Friday is now being asked to self-isolate and come forward for testing immediately if they develop even the mildest of symptoms.
Mr Hazzard said the pub had been directed to close, with contact tracing under way and a pop-up testing facility set up in the venue's car park.
"I suspect the particular hotel's quite a popular hotel and I understand it would have been pretty full," he said.
NSW Chief Health Officer Dr Kerry Chant said they were looking to determine the source who potentially infected both people at the hotel.
The health minister said another troubling case that emerged on Friday was a man in his 20s from Melbourne, who had towed his caravan up from Victoria into the Sutherland area.
He asked people who had "ducked out of Melbourne" just before or after new public health orders to consider "packing up your caravan, packing up your tent or whatever else you've got and head home to Victoria".
"Your government has put in place some very strict guidelines and rules, it's not helpful for you to be out of that environment if you've been in that environment," Mr Hazzard said.
"If you can, go home. Go back to Victoria and go back to your area and comply with your own government's laws."
The two new cases follow the confirmation of a third COVID-19 case in the NSW-Victoria border town of Albury linked to two previous cases in the regional city.
The case, a man in his 30s, is connected to two family members who tested positive to COVID-19 in Albury earlier in the week.
NSW recorded 13 other COVID-19 cases in the 24 hours to 8pm Thursday, all in hotel quarantine, from more than 18,500 tests.
More than one million COVID-19 tests have been carried out in NSW since testing began.
Meanwhile, Mr Hazzard said dozens of people who were tested in the Balmain and Rozelle area have been asked to get retested after 77 swabs were "misplaced in the system".
He said he had asked NSW Pathology to look at what system issues might have caused the error.
Premier Gladys Berejiklian this week warned the Victorian COVID-19 outbreak is a wake-up call and everyone should be "in a state of high alert".
While there was no evidence of increased community transmission across the border yet, she said it would be as long as a fortnight before the situation became clear, with health authorities aware the virus may be "bubbling away" under the surface.
Ms Berejiklian reiterated that all residents of NSW-Victoria border towns should stay put for the time being and those from elsewhere in the state should not approach the border.
More than 125,000 exemption permits were issued by Thursday for people living in NSW-Victoria border communities, allowing them to move between the two.
Queensland's borders opened from midday on Friday for the first time since closing on March 25 to stymie the spread of COVID-19.
Australian Associated Press