New South Wales' Premier has warned residents of the Australian state to brace for a "considerable amount" of COVID-19 cases on Friday, as parts of Sydney go into lockdown.
Gladys Berejiklian's warning comes after case numbers shot up dramatically from four coronavirus cases on Wednesday to 17 on Thursday evening, prompting fears a new outbreak could scupper Christmas plans.
The cases are all part of what's now been dubbed the Northern Beaches cluster, with those living between the Sydney suburbs of Spit Bridge and Palm Beach told to stay at home where possible, refrain from seeing other people and avoid visiting the likes of clubs, restaurants, churches and gyms.
Thursday's escalation in case numbers mean New South Wales is now staring down the barrel of new COVID-19 restrictions just as residents ready themselves for a summer break, during which many would've planned to cross state borders.
In an interview with 7 News on Friday morning, Berejiklian said she was "absolutely concerned" by the prospect of a new COVID-19 outbreak.
"I am asking people to brace themselves today, we are going to see more cases overnight... we are absolutely concerned," she said.
"We are going to have a considerable amount of cases come during the day, and that's because people have come forward for testing."
Six pop-up clinics were set up in the Northern Beaches on Thursday in response to new cases in the area, with thousands of people receiving tests.
In response to the new cluster, most other Australian states have imposed restrictions on travellers who have been in the Northern Beaches region. Western Australia is opting to prevent anyone from New South Wales entering the state unless they quarantine for two weeks.
Before the emergence of this cluster, Australia had largely contained community transmission of the coronavirus.
Prior to an airport worker infection earlier this week, the country last reported a local case on December 3, when a hotel quarantine worker in Sydney tested positive for the virus.
The new 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.