The 12 cases confirmed on Thursday morning include four travellers in quarantine and three cases announced to the public on Wednesday outside the daily figures.

The cases follow days of no confirmed community transmission and put a November 1 reunification with Queensland in doubt.

Ms Berejiklian said the government was considering making a Service NSW QR code for visitors to venues to check in, rather than those through third parties, compulsory.

She said situations where patrons used the same pen to sign in was "just not on".

NSW Chief Health Officer Dr Kerry Chant said health authorities were treating the new cases as two clusters. One was linked to a Liverpool Hospital dialysis outbreak, she said a woman in her 30s.

Dr Chant said the woman hosted a social event in her home while asymptomatic but infected, which is the suspected source of infection for two of the other cases.

"That healthcare worker did not have symptoms, so it's very important to remember that in any reporting."

Four more cases were linked to that case, while one case's source remains under investigation.

They follow late-night updates from NSW Health that flagged Ripples restaurant at Milsons Point on Saturday from 8pm to 10.30pm as a venue visited by an infected case.

"All diners who were in this restaurant at that time are considered close contacts and must immediately get tested and isolate for 14 days since they were there," NSW Health said in a statement.

"Stay isolated for the entire period, even if a negative test result is received."

Anyone who attended Mazda Artarmon's repair centre on Campbell Street between 7.30am and 9.30am last Friday are classed as casual contacts.

They should isolate and get tested if they develop symptoms.

Ms Berejiklian said authorities expected to have more information about locations today, and that indications had emerged that some businesses were not complying with the pandemic requirements.

She urged anyone who arrived at a venue that was falling short of COVID-19 safety to take their custom elsehwere.

"I have no patience any more for businesses in particular who aren't doing the right thing," Ms Berejiklian said.

"We can't have a few people let down the whole community."

Almost 12,500 people were tested in the 24 hours to 8pm Wednesday.

NSW now has a total of 4072 confirmed cases, with one in intensive care.

There have been 55 deaths and more than 2.7 million tests conducted in the state during the pandemic.