Covid 19 coronavirus: Warning over NSW's 'zero day'

Deputy Premier John Barilaro has warned against complacency. Photo / Getty Images

NSW has remarkably recorded a "zero" day of no local cases, however authorities have warned against celebrating too early - as testing numbers are too low and two local cases that missed the 8pm cut-off time for today's numbers.

Both of the new cases are linked to BWS Berala cluster and will be in tomorrow's reported cases.

NSW Acting Premier John Barilaro said far more people need to come forward for testing, after 22,275 tests were done yesterday.

"We're urging those test numbers to well exceed the 30,000," he said.

Earlier he revealed authorities are weighing up another local lockdown in Sydney's west as the acting premier warns there could be "big numbers" of people at risk of infection from a new bottle-o cluster.

Thousands are in isolation after two workers at a Berala BWS, in Sydney's west, worked over a period stretching more than 10 days – with more than 1000 customers passing through the store on Christmas Eve.

Barilaro signalled there could be another local lockdown – like the one in the northern beaches – if the situation worsens. He said it could see the entire Cumberland local council area in Sydney's west subject to the strict orders.

He said the sheer number of customers passing through the store poses a big challenge for contact tracers, but that right now the situation is under control.

"If you look from 22 to 26 December, they could be big numbers, and we will always consider what we can do in relation to a lockdown, further restrictions, especially where there is a hot spot," he told Today.

"One of the things we said when we were lifting restrictions was that if we had to respond, it would be fast and it would be hard and local, just like we have done for the peninsular.

"There is no reason we couldn't do that for Berala, Cumberland LGA area, but right now the data says we are on top of it, and I trust the expert advice we are receiving."

NSW reported eight new coronavirus cases on Sunday while Victoria reported three new cases.

The list of high-risk venues continues to grow for NSW, with health authorities issuing a critical warning for the suburb of Berala in Sydney's west. There are now 13 cases linked to the Berala cluster and 148 linked to the Avalon cluster.