Two Victorians who tested positive to COVID-19 visited venues in Eden and Bermagui on Wednesday and Thursday, NSW Premier Gladys Berejiklian said.
The positive cases visited the Great Southern Hotel in Eden on Wednesday from 5pm to 6.30pm. Contact tracing is under way.
As well, they visited the Bermi's Beachside Cafe in Bermagui on Thursday about 9am to 10am. NSW chief health officer Dr Kerry Chant said they were in the process of contacting that venue.
People who attended the venues at that time have been asked to get tested and isolate. NSW Health will provide further advice.
Details were scant on Friday morning as they had come "hot off the press", Dr Chant said.
But it has since emerged the two Victorians who had tested positive had travelled to NSW. The cases are linked to Victoria's Smile Buffalo Thai Restaurant in Block Rock cluster. They were tested for the coronavirus while they were in NSW and have since returned to Victoria.
The two cases are not included in either the NSW or Victoria daily totals. The Canberra Times has contacted NSW Health and the Department of Health and Human Services Victoria for further information.
Earlier, Dr Chant said the Victorians had indicated they might have a link with someone who had travelled to Sydney but she confirmed that person had tested negative.
People in the Bermagui area have been urged to monitor for symptoms.
"It is important if you are hearing this and you know anybody within the Bermagui area that you reach to them and make sure that they are aware of the situation," Dr Chant said.
"We understand that there may be a lot of visitors who have travelled to that part over the festive season."
In a post on social media, Bermi's Beachside Cafe said it was waiting for further advice from NSW Health.
"We haven't been given any further details however all staff have been contacted and are all getting COVID tested and are in isolation awaiting results and instructions from the health department," the post said.
"We are very confident in our COVID safety plan and have followed all rules [and] enforce these rules to keep everyone safe.
"Anyone who visited the [cafe] at these times will be contacted."
Victoria has established a hard border with NSW, which will take effect from 11.59pm on Friday. Victorian holidaymakers have rushed to make it back across the border and there are slow-moving queues at checkpoints.
Many of these have come from the NSW far south coast, which is a popular tourist destination for Victorians.
ACT chief health officer Dr Kerryn Coleman encouraged any Canberrans who were at the locations to check the NSW Health website for further information.
"These new case locations are a reminder that all Canberrans who have travelled to the South Coast over Christmas and New Year, should monitor the NSW Health website to see if they had any cases in any of the areas you visited for two weeks after your return," Dr Coleman said.
It came as NSW recorded three locally acquired cases of COVID-19 in the 24 hours to 8pm on Thursday from 32,000 tests. All were located in Western Sydney, two members are from the same households.
There were no new cases in the ACT, and there is currently only one active case in Canberra - a Commonwealth official who returned overseas and is in hotel quarantine.
Travel restrictions between the ACT and greater Sydney have been in place since December 20. Anybody who visits greater Sydney, Blue Mountains, Wollongong and Central Coast is required to quarantine for 14 days upon return.
There are no travel restrictions between ACT and regional NSW but authorities have urged Canberrans to reconsider non-essential travel. Sydneysiders can travel freely within regional NSW.