There were 19 new cases of COVID-19 found in NSW in the past 24 hours period, with two of those identified in overseas travellers.
The rest, NSW Health's Dr Jeremy McAnulty said, were linked to exisiting venue clusters throughout Sydney.
He said three were linked to Bankstown's funeral gathering cluster, while 10 were linked to Thai Rock in Wetherill Park.
Two more were linked to Thai Rock in Potts Point, which is owned by the same people as the Wetherill Park eatery, Dr McAnulty said.
He also NSW Health was increasingly concerned about the outbreak in Potts Point, as another staff member at the Apollo restaurant in the suburb tested positive to the virus.
One more case was linked to the Crossroads Hotel at Casula.
Dr McAnulty said there were more than 18,000 people tested in the 24 hours to 8pm, and the state had now recorded 3529 COVID-19 cases since the start of the pandemic.
With new case numbers rising but staying relatively steady for a number of days, Dr McAnulty said people should be checking the NSW Health website on a regular basis as more venues were identified as hot spots.
"We are at a knife's edge, a very critical point in the cases," he said.
"The good news is that we are able to link them all together. [This means] we can understand the transmission dynamics and the people at risk."
Also at the morning update, Premier Gladys Berejiklian said the state remained on high alert, but said contact tracers had done "an unbelievable job" and quickly identified venues and contacts so the state could "hold the line" on the spread of the virus.
"We have the opportunity to get through the next few weeks and continue on our strong path," she said.
If this does not happen, she said further lockdown measures may need to be considered.
"I'd much rather [it] be harder now than have to deal with a worse situation in a few weeks time," she said.
She announced that gyms would now be required to have a COVID safety plan in place and hygiene marshall on shift at all times, even at 24-hour venues which sometimes operate without staff.
"I also want to stress the importance of social distancing," she said.
"The 1.5 metres has to be part of our lives for the duration of this pandemic. And if you can't maintain social distancing, you should be wearing a mask."
Minister for Customer Service Victor Dominello said the extra measures for gyms were necessary to stop the spread of the virus. They will take effect from 12.01am on Saturday.
"We cannot afford to take any risks or allow complacency to creep in," he said.
"Businesses must take all reasonable steps to reduce the risk of COVID transmission or risk facing a fine or closure.
"Gyms play a crucial role in the promotion of health and fitness across our community but they are not immune from this challenge.
"Without proper COVID safeguards, they may present a transmission risk and that is why we need operators to put their customers first by registering their COVID Safety Plan.
"Whether it's maintaining social distancing, cleaning equipment after use or making hand sanitiser available for customers, these dedicated COVID Safe Hygiene Marshalls will play a pivotal role in keeping gyms safe and compliant."
Meantime, with the Sydney outbreak growing, Queensland Premier Annastacia Palaszczuk announced her state would close its borders to all of Greater Sydney.
"From 1am Saturday, no one from Sydney will be allowed into Queensland," she announced, as the NSW morning media update was unfolding.
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