Two men, both aged in their 90s, have died from COVID-19 as NSW recorded 345 new cases on a record day of testing.
There are 374 cases in hospital, 24 require ventilation, and 62 are in intensive care.
The latest 24-hour case numbers announced Thursday included also revealed that there were at least 60 COVID-positive people infectious in the community.
The two men in their 90s died in Sydney hospitals, including one who became the seventh death associated with the Liverpool Hospital outbreak.
One man had received both doses of Pfizer, while the other had received only the first.
Ms Berejiklian said the front had moved in Sydney to Cumberland local government area, particularly Auburn and Granville.
Bayside, Strathfield and Burwood local government areas have been added to the areas of concern.
152,000 tests were conducted in a "huge record", Ms Berejiklian said.
Newcastle's lockdown will last at least another week, NSW Premier Gladys Berejiklian has confirmed.
Armidale, Tamworth and Northern Rivers had no new cases in Thursday's update.
"Unfortunately the same isn't the case for Hunter and New England," Ms Berejiklian said, citing NSW Health advice.
"Given what the area's experience I think the community would understand why [the lockdown extension] is the case."
Ms Berejiklian said she would take advice from NSW Commissioner Mick Fuller on whether further health orders were required to stop the virus spreading.
"We know it only takes a handful of people doing the wrong thing every day to create major setbacks, she said.
"We're still recovering from gatherings that were illegal, we're still recovering from people doing the wrong thing because that has a cumulative effect day on day."
NSW chief psychiatrist Dr Murray Wright described the lockdowns across the state as the most sustained and severe stress many NSW residents would deal with throughout their lives.
He urged people to assume others were dealing with high stress, to check on loved ones and to seek help through organisations including BeyondBlue if their alcohol intake, sleep or concentration fluctuated.