Coronavirus restrictions are expected to be extended in NSW as a cluster continues to expand across Sydney.

Masks became mandatory in several settings on Sunday, as the Bondi outbreak reached a “critical phase”, and people were urged to curtail their movements.

On Monday, state health authorities urged Sydneysiders to avoid gatherings, minimise movements and work from home if possible.

Premier Gladys Berejiklian indicated the rules, which had been imposed for just a few days, were likely to be extended to fight the Sydney COVID cluster.

“I can foreshadow that it’s likely we will have to continue with the existing settings in place past Wednesday night,” Ms Berejiklian said.

Two more COVID-19 cases were detected in the community on Monday, bringing the total number of infections connected to the Bondi cluster to 11.

Both were diagnosed after Sunday’s 8pm cut-off and will officially be included in Tuesday’s numbers.

On Monday afternoon, NSW Health added several bus routes to its rapidly expanding list of exposure sites. The include the Sydney-Baulkham Hills (and return route), where anyone who travelled at designated times is considered a close contact and must isolate for 14 days.

Tweet from @NSWHealth

Ms Berejiklian said authorities remained concerned by the extremely contagious nature of the Delta strain of COVID-19.

“In some instances, the exchanges have been scarily fleeting,” she said.

“People not even physically touching each other but literally fleetingly coming into the same airspace has seen the virus transferred from one person to another.”

The state government has resisted imposing strict lockdown rules, but next steps will be influenced by testing numbers.

“We do not want to see further restrictions imposed than we already have,” Ms Berejiklian said.

“But the higher the testing rate the more confidence we have knowing the policy settings are adequate.”

Of Monday’s two new local cases, one is a woman in her 50s who lives in Sydney’s northern suburbs, the other a man in his 30s from the eastern suburbs.

They are both close contacts of previously reported cases and have been in isolation while infectious, which chief health officer Kerry Chant said was a good sign.

“It shows the robustness of isolation, and that’s an optimistic sign,” Dr Chant said.

But she also said NSW was not out of the woods.

“From one person alone we’ve had four or five cases … even if they infect one or two each, you can see how it grows exponentially,” she said.

“That’s why this is such a critical phase.”

Another two cases, announced on Sunday morning, were recorded in the 24 hours to 8pm on Sunday and were included in Monday’s figures.

Tweet from @NSWHealth

NSW Health said those without symptoms who have visited exposure sites at the listed times had no need to to isolate.

“However, everyone is strongly urged to avoid gatherings and minimise their movements, such as attending cinemas or trips to skifields,” the department said.

“If you can work from home, please do so.”

On Sunday, Ms Berejiklian said the days ahead would be “critical” to avoid a super-spreader event.

“The next few days are critical. We ask people not to be complacent. If cases continue to emerge we will need to go further. We are nowhere near having vaccinated the majority of our population yet,” she said.

• See an updated list of NSW virus rules here

In the local government areas of Randwick, Bayside, Botany Bay, Inner West, City of Sydney, Waverley and Woollahra, masks must be worn by anyone shopping, working in hospitality or attending indoor public venues – unless eating or drinking.

They are also compulsory on public transport in greater Sydney, Wollongong and Shellharbour local government areas until at least Thursday.

Greater Sydney and Blue Mountains residents have been told to avoid non-essential visits to aged care and disability facilities and if visiting must wear a mask with a limit of two visitors a day.

Dozens of venues across Sydney have been visited by COVID-positive people since June 11, and health authorities expect more sites to be added as contact tracing investigations continue.

By Monday afternoon, high-risk locations stretched from Fairy Meadow in the south, into the Hills Shire to the north, as well as more across the CBD, suburban Sydney and Campbelltown.

Twenty-seven new exposure sites were listed on Sunday, including a North Face outlet in Drummoyne.

More casual sites in Drummoyne, along with others at Castle Hill, Merrylands, central Sydney and Hurstville were also added.

Meanwhile, Victoria confirmed one additional local case of coronavirus on Monday.

Four more Sydney LGAs became “orange zones” under Victoria’s border permit system. South Australia has joined Queensland in imposing an immediate ban on travellers from the Waverley Council area.

-with AAP