Premier Gladys Berejiklian said nearly 63,000 people came forward to be tested on Monday.

She said the new testing requirements for people working outside Greater Sydney had uncovered a number of asymptomatic positive cases.

Ms Berejiklian said it was positive the overall number of cases had dropped but work needs to be done to reduce the number of people in the community while infectious.

"I'm convinced if we all work together and focus on those key areas of concern... we will get through this," Ms Berejiklian said.

IN OTHER NEWS:

Chief Health Officer Kerry Chant emphasised that COVID was a serious disease which put people in ICU and on ventilators.

"We had to stop the spread of COVID, to do this we all need to work together, we need to limit our movements we need to consider anytime we leave our house anyone we come into contact will [could have the virus]," she said.

Dr Chant said it was human nature to be friendly, but people should not be starting conversations in public.

She said now was the time to limit interactions with others.

Watch Gladys Berejiklian speak live below.

This morning, South Australian Premier Steven Marshall announced the state would be locked down for five-days in response to growing COVID cases.

So far five cases have been identified in South Australia.

It comes as Victoria recorded 13 cases of COVID-19, four of which were announced yesterday.

One of the cases has not been linked to an existing cluster.

Victorians are due to find out exactly how long the current lockdown will last, later today.

Yesterday, Victorian Premier Daniel Andrews foreshadowed the tightening of border restrictions.

He said the state had to 'defend' itself from the outbreak in NSW.

"Just in terms of the border, I'm not here today to make announcements but we are actively looking at what more we can do," Mr Andrews said.

"It's a pretty hard border now, police are using technology, drones, choppers they're doing random stops, they're doing all sorts of things, and overall compliance with the permit system has been very, very high.

"But I certainly can't rule out further changes and further limiting of movement from NSW to Victoria."

We have removed our paywall from our stories which contain need-to-know information about coronavirus. If you would like to support our journalists you can subscribe here.