New South Wales has recorded two locally acquired cases in the past 24 hours after the state brought in mask rules in a bid to combat the spread of the virus.

One of the cases was announced on Friday morning and is included in Saturday's numbers.

The new case on Friday was a man in his 50s who attended Bondi Junction Myer at the same time as a limousine driver who tested positive to Delta variant earlier this week.

The driver has not been vaccinated and his passengers include international flight crews, raising concerns over unvaccinated frontline staff.

The second case is a woman in her 40s who attended a number of venues in Bondi Junction.

NSW Health Minister Brad Hazzard said Friday's case was between to 10cm and 60cm away from the driver when authorities believe he caught the virus.

Hazzard said it was "no more than seconds" that the two men were near each other at the shopping centre.

"This Delta virus would appear to be a near and present danger," he said.

NSW Health said 1100 contacts had been tested and were in isolation, as additional venues at Bondi Junction, Macquarie Park, North Sydney, Newtown and Campbelltown were added to its list of exposure sites.

Concern over lack of restrictions

Masks are compulsory on public transport for Greater Sydney and the Blue Mountains, but not in Wollongong and on the Central Coast. The new rule will be in place until next week.

Looking at the growing outbreak, UNSW epidemiologist Mary-Louise McLaws said yesterday that it was time for authorities to take stronger action.

"We're in trouble, now we know the strain is Delta," she told the ABC.

"Restrictions need to be [implemented] strictly and quickly because this virus has learnt how to be highly infectious and doesn't need a lot to spread.

"It's up to 70 per cent more infectious than other strains, so it's very problematic."

The current outbreak in Sydney is of the more transmissible Delta variant. (Photo / Getty)

Despite the warnings, NSW Premier Gladys Berejiklian has stopped short of adding restrictions to gatherings or mandating masks in public places.

Instead, Berejiklian residents in Sydney to be on high alert and advised them to avoid big social events.

"Unless you absolutely have to attend a large gathering, unless you absolutely need to engage in activity of a social nature in next few days, we ask everybody to refrain from that," she said yesterday.

"Assume that everybody you're in contact with has the virus and assume you have the virus yourself and that's the best advice we can give you as the next few days unfold."