Sydney on Tuesday reported four new coronavirus cases linked to a second active infection cluster involving a liquor store in the Australian city's western suburbs.
With the new cases, the cluster detected in the Berala suburbs has increased to 15, Xinhua news agency reported.
Health officials, however flagged an additional case, detected overnight and not included in Tuesday's figures, which involved an 18-year-old man who travelled to vulnerable regional communities in the New South Wales (NSW) state, of which Sydney is the capital.
"An 18-year-old man travelled from Berala to Orange, Nyngan and then Broken Hill for a camping trip," Acting NSW Premier John Barilaro said.
"This is a reminder of what can occur for people who are moving out of Sydney."
Officials urged residents from those towns to be tested, with plans to establish additional testing clinics.
Meanwhile, the state of Victoria reported three additional Covid-19 cases attributed to a Thai restaurant cluster involving a total of 27 infections, which authorities said was linked to the Sydney outbreak.
Starting Monday, wearing of face masks became mandatory for all residents of Sydney in public indoor spaces and on public transport for the first time since the pandemic began.
The first cluster was detected late last month in Sydney's Northern Beaches area.
The state of NSW currently accounts for 4,973 coronavirus cases and 54 deaths.
Australia has so far reported a total 28,504 cases and 909 fatalities.