New South Wales is staring down the barrel of Christmas COVID-19 restrictions after 17 cases were recorded in 24 hours.
On Thursday the state reported a slew of confirmed cases with no known link to the border, and residents of Sydney's Northern Beaches have been asked to stay at home.
Five initial cases were detected in the area on Wednesday and Thursday, and a further 12 were reported on Thursday evening.
The Northern Beaches cases currently have no known links to the border and the sources of infection are unknown.
Western Australia has stopped short of closing its border with New South Wales, but has imposed strict restrictions for anyone entering, effective immediately, reports 7News.
Anyone who has arrived from NSW since December 11 or was in NSW from December 11 and subsequently arrived in WA needs to self-quarantine in a suitable premise as soon as possible.
They must receive a COVID-19 test within the next 24 hours, and then quarantine again until it returns negative.
Anyone flying in must also be tested, either on arrival or within 24 hours. They must also self-quarantine.
Western Australia premier Mark McGowan says he will not hesitate to take further steps if necessary.
"We ask for your patience and understanding as we take these steps to protect the health of all Western Australians."
Australia had largely contained community transmission of the coronavirus. Before the airport worker infection, the country last reported a local case on December 3 when a hotel quarantine worker in Sydney tested positive for the virus.
The cases raise fresh questions over a potential trans-Tasman travel bubble, with the New Zealand Government saying one would only proceed should Australia go 28 days without a local case.
