Officially, Newcastle and the Hunter recorded 26 new cases of COVID-19. But NSW Health confirmed on Monday morning that 84 people have now been linked to the Newcastle nightclub exposure - 60 of these overnight.

These new cases will be reported in tomorrow's figures.

"A number of these cases are likely to be the Omicron variant," a NSW Health spokesperson said.

Lake Macquarie MP Greg Piper said NSW Health had confirmed that the number of cases now linked to Argyle House is 84, up from what was reported this morning.

In the 24 hours to 8pm on Sunday, there were 28 positive cases of COVID-19 throughout the entire Hunter New England Health district.

So far, a returned traveller is the only confirmed case with the Omicron variant, and the local health district says that person and their close contacts have been isolating at home.

But NSW Health has warned that a "number" of the now confirmed cases who attended Argyle House last week are "likely" to have the Omicron variant, but that was yet to be confirmed via genomic sequencing.

Of the new cases officially announced on Monday, 12 are from the Newcastle LGA, nine are from Lake Macquarie and three are from Maitland.

There is one case in Port Stephens, one from Muswellbrook, one in Tamworth, and another from the Mid Coast LGA.

The Newcastle Herald reported earlier that the household contacts of anyone who attended the Argyle House nightclub on Wednesday night to Thursday morning last week are also being urged to test and isolate given the high transmission of COVID at the venue.

Argyle House hosted a "prom night" event on Wednesday, December 8.

Now 84 people linked to the Argyle House nightclub exposure have tested positive for COVID-19.

All 680 people who checked in using the QR code to attend the venue from 9pm, on December 8 until 3am on December 9 have been assessed as close contacts and must immediately get tested and isolate for seven days.

NSW Health is appealing for anyone who did not check in using the QR code to urgently get tested and isolate, and for the community to ensure other potential attendees are aware of this advice.

"Given the high transmission of COVID-19 at the venue, we ask household contacts of anyone who attended to also immediately get tested and isolate until the close contact tests negative," NSW Health says.

"Everyone should remain vigilant when celebrating with family, friends and colleagues and should not attend any social functions if they have any symptoms."

COVID-19 case alerts also went out to people who attended the Great Northern Hotel on December 10 through to December 11.

There were long queues for Hunter testing clinics for the first time in weeks on Monday morning as residents flocked to COVID testing sites.

Across NSW, there is now a total of 64 cases of COVID-19 with the Omicron variant of concern, with more expected as results of genomic testing are confirmed.

Newcastle MP Tim Crakanthorp urged people to keep an eye on their Service NSW app for case alerts and look out for any symptoms.

"This is a naturally concerning situation but I have every confidence we will be able to get on top of it," he said.

"Many of us will be seeing vulnerable friends and family over this Christmas period, which makes it even more important to be tested no matter how slight the symptom is and ensure we keep our loved ones safe.

"We have heard a lot over the last two years that we are all in this together, and we all have a part to play in protecting each other by getting vaccinated if we can, getting tested if we display symptoms, and staying home if we are unwell."