Australian health officials are investigating how a COVID-19 quarantine hotel worker in Sydney became infected with the virus.
New South Wales Health was notified of the case late on Saturday night and announced the infection on Sunday. It is the first locally acquired case in the state in 55 days.
Health authorities said the infected person had worked at two Sydney hotels.
"The source of the new infection reported overnight is under investigation and urgent genome sequencing is underway," says Dr Stephen Conaty, director of population health at NSW Health.
NSW Health says testing of the worker's close contacts is underway.
The infected person will be included in Monday's case numbers. As of Sunday, the total number of cases in the state is 5048.
This new case comes at the same time as a Queensland quarantine hotel will remain in lockdown while health authorities investigate a potential COVID-19 transmission inside the facility.
Dr Sonya Bennett, Queensland Health's deputy chief health officer, says partial genomic sequencing indicates there's a link between a Brisbane doctor who tested positive on Friday and the traveller's positive case that was announced on Saturday.
The traveller, who was staying at the Grand Chancellor Hotel in Brisbane, tested positive on their day 12 exit test. They had been staying on the same floor as a patient with the UK strain of the virus who was later transferred to Princess Alexandra Hospital, which is where they're believed to have infected the doctor.
Queensland Health is investigating whether the traveller caught the virus while in quarantine or if they always had COVID-19 but only tested positive on day 12.
In response to the doctor testing positive, NSW Health asks anyone who has arrived from Queensland after March 11 to check the Queensland Health website for public health advice.
"Several venues of concern in Brisbane have been identified and are listed on the Queensland Health website. Anyone who has attended any of these venues during the relevant times is asked to immediately self-isolate," they say.
If symptoms occur, people are asked to get tested immediately and isolate until they receive a negative result.