Testing numbers across southwest Sydney have been high in recent days.
NSW recorded 97 new locally acquired COVID-19 cases in the 24 hours to 8:00 pm yesterday.
Twenty-nine of the people who tested positive were out in the community for the entire time they were in the community.
Another 17 were isolated for only part of the time they were infectious.
NSW Chief health officer Dr. Kerry Chant said the fact that so many were still going about their normal business was "incredibly concerning".
"I can't stress to the community my absolute concern that we need to work harder at reducing mobility and reduce our interactions with others if we will bring the situation under control," she said.
Also concerning to health authorities is the fact that the source of 34 of the new cases is unknown.
"We have a number of cases under investigation and seeing the emergence of unlinked cases which is a matter of concern," she said.
Premier Gladys Berejiklian warned the number of cases would likely be higher tomorrow and flagged tougher restrictions may be needed to combat the outbreak.
"There is no doubt that the numbers are not where we would like them," she said.
"Please know that every day on an hourly basis we receive ongoing reviews and we make sure we review all the time the settings we have in place.
"If we need to go harder, of course, we will."
Ms. Berejiklian said her government would "not hesitate to take any decision we need to, to make sure those numbers go down".
The Premier said how long the lockdown would need to continue depending on the community's response.
"I know the sentiment that exists in greater Sydney including with all of us is that we want to end this lockdown as soon as we can," she said.
"We don't want this to drag on and we know the community wants us to do more, so long as that means the lockdown is not extended for a longer period and that is our focus."
There were 77,500 tests carried out yesterday, a new record for daily testing in NSW.
Dr. Chant said that was in large part due to the community in Fairfield coming out for testing.
"I say a big thank you to the community," she said.
But she warned that there was no room for complacency in other parts of Sydney.
"We are seeing [cases] pop up in other local health districts and other local areas and there is a lag in the data," Dr. Chant said.
"So absolutely you have to be vigilant no matter where you are across New South Wales in general and in Sydney specifically."
There have now been a total of 466 new cases of COVID-19 in NSW this week.
The highest number of daily cases was on Monday when 112 tested positive.
There are 75 people with COVID-19 being treated in hospital, including 18 in intensive care and five of whom are on ventilators.
Of those in hospital, 30 are under the age of 55.