NSW health authorities have admitted they have missed months of transmission of the coronavirus in south-western Sydney as they try to pinpoint the origins of a spike in community cases.

Premier Gladys Berejiklian sounded the alarm on Wednesday as NSW confirmed 13 more COVID infections.

Among them were 11 community cases, nine linked to an expanding cluster at a Lakemba GP clinic. The other two are people in hotel quarantine.

Ms Berejiklian said NSW was poised at the most worrying point since an outbreak started at the Crossroads Hotel in Cassula, in Sydney’s south-west in July.

“Some of the new cases that have emerged in south-western Sydney tells us, and [chief health officer Kerry Chant] explained this in great detail this morning, there was some chains of transmission we hadn’t picked up weeks or months ago,” she said.

“It’s really important for us to make sure that we’re not missing any of those chains of transmission.”

The Lakemba GP outbreak has grown to 12, all household contacts of known cases. Hundreds of patients who visited the practice are being traced.

Health authorities are still investigating the source of the cluster, but believe it links back to another south-western Sydney GP.

The other two new locally transmitted cases are linked to the private clinic cluster, which grown to 10. One attended the clinic, while the other is a staff member.

Dr Chant said it was “reassuring” that Wednesday’s cases were connected to known clusters.

“[But] due to the large nature of the contacts that we’ve had to do, the multiple venues, all of that means that there is potentially infectious people in many settings,” she said.

But the index source of the latest outbreaks had still not been found.

“We’re still trying to unravel the source of the clusters and this is the time we’re asking the community to come forth and get tested, but also maintain those COVID safe practices,” Dr Chant said.

Authorities are also worried about a case that has been discovered in Bargo, south-west of Sydney. Photo: AAP

Another positive case – a man in his 70s – was diagnosed in Bargo, south-west of Sydney, after Tuesday’s 8pm cut-off. It will be officially included in Thursday’s figures, but all residents of the town have been urged to be on the lookout for COVID symptoms.

Testing has been stepped up in the town, as the man is interviewed to try to determine the source of his infection.

• See a full list of NSW venues of concern here

On Tuesday, the NSW government announced hospitality restrictions would be eased from Friday, with up to 500 people allowed to attend open-air concerts as long as they stay seated and four metres apart.

Restrictions for outdoor dining venues will also be relaxed, allowing one patron per two square metres as long as venues use an electronic QR code to record patrons’ contact details.

On Wednesday, Ms Berejiklian said she had planned to announce more restrictions would be wound back. But the jump in cases meant she had decided to hold off until Dr Chant gives the green light to go further.

Meanwhile, public health alerts have been issued for shops and restaurants in Sydney’s south-west as authorities work to suppress the hotspot’s virus spread.

A pop-up testing clinic has been set up at Julia Reserve Community Centre in Oran Park and authorities are urging people to get tested.

While 16,000 tests were conducted in the 24 hours to 8pm on Tuesday, almost double the number on Monday, Health Minister Brad Hazzard said that was not enough.

“The numbers that we got overnight are just reminiscent to me of Crossroads [outbreak] and it worries me that perhaps the community are not actually coming out in the numbers that we need to be tested,” he said.

“Just thinking you might have hay fever is no excuse to not get tested.”

Mr Hazzard said health authorities wanted more than 20,000 people to be tested each day.

-with AAP