Two cases - a man in his 40s and a man in his 20s - are under investigation after 32,000 people came forward for testing in the 24 hours to 8pm on Thursday.

The third case, a man in his 20s, is a close household contact of one of the other two men.

None of the three new cases are linked to the northern beaches hotspot which now totals 146 after two previously recorded infections were linked.

The state government is urging western Sydney residents from Greystanes, Auburn, Berala and Lidcombe with even the mildest of symptoms to get tested.

Patrons who dined at the Swallowed Anchor restaurant in Wollongong on December 19 have been urgently called after one case from Croydon and another from the local area both attended on that date.

"There may have been a transmission event at that venue," NSW Chief Health Officer Kerry Chant said.

Prime Minister Scott Morrison said the recent low numbers recorded in NSW were encouraging and thanked the community for listening to health advice and coming forward for testing.

"COVID still hasn't gone away, it hasn't taken a holiday, it won't be going anywhere, and as a result, we continue to deal with the very serious challenges," Mr Morrison said.

Meanwhile, the mystery source that sparked the Croydon cluster and two cases in Wollongong has now been linked to the Avalon cluster, with the connection between the cases revealed by genetic testing.

Other alerts for Eden and Bermagui on the south coast come after two coronavirus cases travelled to NSW from Victoria on December 30.

Anyone who visited the Great Southern Hotel in Eden that afternoon should get tested and isolate until further advice, as well as Bermi's Beachside Cafe in Bermagui on the evening of December 31.

At the southern NSW border, Victorians are facing lengthy queues to cross into their home state after it imposed travel restrictions from midnight on Friday, with anyone arriving after that time having to spend a fortnight in quarantine.

Premier Gladys Berejiklian said the border closure was not the best use of resources.

"I think we're better off asking the community to come forward to get tested, cutting off those chains of transmission, making sure everybody has enough information about venues and about COVID safe activities," Ms Berejiklian said.

New year revellers in the state were congratulated for keeping events low-key with NSW Police Assistant Commissioner Mick Willing saying the CBD was quiet and restrictions were generally adhered to.

Large crowds in the Villawood area watching illegal fireworks were broken up while an Airbnb party in the Hills district prompted 30 infringement fines.

On Thursday NSW reported 10 cases of community transmission with five linked to Sydney's northern beaches cluster.

The growth in locally acquired COVID-19 cases in greater Sydney prompted the NSW government to limit home gatherings for New Year's Eve to five visitors, down from 10, and outdoor gatherings to 30, down from 50.

Sydneysiders were mostly banned from watching the city's New Year fireworks from the harbour, with the foreshore fenced off.

New health alerts were also issued on Friday for Bunnings in Ashfield on December 28, Woolworths at Strathfield Plaza on December 20, Woolworths at Berala on December 24, 26, 28, and Haberfield's Clark Rubber on December 28.

Stay-at-home orders applying to northern beaches residents north of the Narrabeen Bridge will continue until at least January 9. A lockdown for the peninsula's southern zone will be in place until January 2.

Both Victoria and South Australia on Thursday also announced they would establish hard border arrangements with NSW, joining Western Australia.

Australian Associated Press