NSW's three new coronavirus cases, close contacts that contact tracers missed, were out and about in the community while infectious, the state's chief health officer has admitted.
The new cases come as thousands of Sydney residents celebrate "Freedom Day" after being stuck in lockdown since before Christmas.
The three new cases, two linked to the Berala cluster and one to the northern beaches cluster, are all close contacts of known cases.
Chief Health Officer Dr Kerry Chant on Sunday told reporters contact tracers had only recently identified the three as close contacts.
"They were in the community infectious for a period of time," she said.
"As you can imagine, people do their best in giving us a history of who attended their house or who they had contact with (but) there are always times where that fails."
"We do occasionally find people that have been missed because people forget to tell us despite everyone's best endeavours."
A number of new venues including the Costco in Casula, a number of shops at the Bankstown Central shopping centre and a supermarket in Marrickville have been declared potential exposure sites.
Meanwhile in the northern zone of Sydney's northern beaches, residents have celebrated the first day of eased restrictions in the area.
"People are calling it Freedom Day," Northern Beaches Mayor Michael Regan told AAP.
People have been out in droves - socially distanced and mask clad - to dine at their favourite local cafes, get their nails done, and even celebrate a very late Christmas Day, he said.
"I was speaking to some people I ran into... and the kids, aged one and a half and three, were so excited to be going to see the grandparents for Christmas."
"It's been tough, we missed the busiest time of the year with Christmas and family... but there was that spirit 'we're gonna do the right thing and beat this' and get back to normality again."
But Mr Regan says the lifting of restrictions comes with its own challenges, and residents are now concerned about transmission from Greater Sydney.
"There's lots of positives today but a bit of anxiousness too obviously."
Ms Berejiklian thanked the area's locals, but in the same breath urged all Sydneysiders to stay on high alert.
"The main threat has to some extent subsided, (but) we are still mopping up," Ms Berejiklian told reporters on Sunday.
"And that's why all of us have to be on high alert.
"The risk in Greater Sydney is the same today as it was last week, because it only takes one or two cases to get out of control."
Three new cases were also recorded in hotel quarantine, as concern about mutated strains of the virus reaching Australia grow.
Ms Berejiklian again implored other states to trust NSW's capacity to wrangle outbreaks.
"I just ask our other state leaders to please talk to us before they close the border to New South Wales, and give us a chance to demonstrate our capacity to get on top of the virus without adversely impacting our citizens," she said.
"When NSW closed its border with Victoria, I spoke at length to the Victorian premier (and) I spoke to the Prime Minister, we had a three- way conversation... and I just ask that other state premiers extend the same courtesy."
But Victorian Health Minister Martin Foley has rebuffed Ms Berejiklian's comments, saying Victoria did brief NSW before they publicly announced the border would be shut on New Year's Eve.
Australian Associated Press