Seven new local COVID-19 cases in NSW

All were recorded in the 24 hours to 8pm on Saturday and are linked to the northern beaches, Premier Gladys Berejiklian said on Sunday.

Six are confirmed as part of the Avalon cluster, bringing the number of cases in the outbreak to around 122.

The seventh case, a firefighter who works at Crows Nest but lives on the northern beaches, is still under investigation.

Three fire stations have been closed for deep cleaning and Fire and Rescue NSW is working with NSW Health to identify all contacts.

The firefighter attended the northern beaches' Belrose Hotel on December 11 and authorities are urging anyone who visited the pub in December to be tested if they have symptoms.

This is in light of other mysterious connections between the hotel and confirmed virus cases.

A 20-year-old worker at the hotel was found this week to have been suffering the virus in early December.

However he didn't cross over with the firefighter and doesn't appear to have transmitted the virus to his close contacts.

To complicate matters, another positive case visited the Belrose Hotel bottle shop on December 17, at a time when the 20-year-old was working.

"We are again renewing our calls for wider spread testing around the Belrose Hotel to help us find any further links between how this virus got into the northern beaches community," chief health officer Kerry Chant said.

People at the pub between midday and 6pm on December 11 should be tested, even if they have not had symptoms, to help piece the puzzle together, she said.

Ms Berejiklian urged NSW residents to keep getting tested to help inform decisions about New Year's Eve and the first few weeks of January.

She promised a decision by Tuesday at the latest.

Testing numbers have nose-dived in recent days.

Over 39,000 people were tested on Friday and the record was set at nearly 70,000 earlier in the week. But they are still markedly higher than before the Avalon outbreak started.

Five of the new cases were already in isolation and a number were diagnosed on day 10 or 11 of their confinement, Ms Berejiklian said on Sunday.

Another case has been picked up linked to the Rose of Australia pub at Erskineville and a household contact has also tested positive. These numbers will be included in the count for Sunday as they came back after 8pm.

Dr Chant pointed to these cases to emphasise the importance of staying in isolation for 14 days and getting tested towards the end of the period.

Meanwhile, new alerts have been issued for a number of venues in Sydney's inner west, as well as in Centennial Park, North Sydney and the northern beaches.

A bus route between Mona Vale and Wynyard also has an alert.

The stay-at-home order imposed on northern beaches residents has been reinstated after a three-day Christmas reprieve.

Indoor gatherings are banned again but outdoor get-togethers of up to five on the northern end of the peninsular are permissible and up to 10 on the southern end.

People may neither enter nor exit the local government area.

NSW Health reminded northern beaches councils on Sunday that none of the rules prevent beaches being open. The 21 beaches between Manly and North Palm Beach have not had full lifesaver patrols since December 18 because of the outbreak.

"Surf lifesaving availability is for Councils to determine but it is considered usual arrangements should apply," the NSW Health statement says.

For the rest of Sydney as well as Wollongong, the Central Coast and Blue Mountains, 10-person private gathering restrictions again apply.

Meanwhile, police have condemned a number of outdoor parties at Byron Bay which breached the 100-person limit on outdoor gatherings.

Australian Associated Press