New South Wales says COVID-19 cases at 3-day low

Australia's most populous state reported on Monday its lowest one-day rise in new COVID-19 cases in three days.

The news has raised hopes that authorities may have managed to contain an outbreak in Sydney's northern beachside suburbs, where 250,000 people are on day three of a five day lockdown.

Fifteen new cases were reported on Monday, compared to 36 the day before.

But more than 80 locations, including cafes and gyms, across Sydney were identified as having been visited by people who've since tested positive.

New South Wales premier Gladys Berejiklian said restrictions may need to stay in place for Christmas:

"We need to monitor and make a final call on Wednesday as to what Christmas and the next few days will look like. And I appreciate people have plans in place. I mean my family is no different to anybody else's. We all, I think that we all empathise with each other."

The government also confirmed it had detected cases in returned UK travellers of the fast-spreading new coronavirus strain found in Britain.

But that the Sydney cluster strain did not have the mutations.

The original source of that cluster is still unknown, but tests show the strain is almost identical to the one found in a woman who arrived in Sydney from the United States earlier this month.

Meanwhile, other Australian states and territories have moved quickly to close their borders to all of Sydney's 5 million residents.

Dozens of domestic flights due to leave the city on Monday were cancelled.

And states have begun operating checkpoints along the border with New South Wales.