Shellharbour, in the Illawarra, has now joined Greater Sydney, the Blue Mountains, Wollongong and the Central Coast in lockdown until 11.59pm on July 9.

More than five million people are affected by the NSW restrictions. Some 52,400 NSW tests were conducted on Saturday.

The Shellharbour local government area, south of Wollongong, was added after the Baby Bunting shop in Shellharbour Park had been identified eight days ago as a place of potential casual contact.

NSW Deputy Premier John Barilaro confirmed on social media on Saturday that "due to the work interconnectivity between Wollongong and Shellharbour, NSW Health has now included Shellharbour as part of the lockdown. Just spoke to the Minister".

NSW Premier Gladys Berejiklian warned on Sunday that "cases may well rise in the next few days".

ACT Chief Minister Andrew Barr has expressed his concern after it was revealed that nearly 19,000 people had travelled back to the territory from the Greater Sydney region since the current Bondi COVID-19 cluster was first identified.

Anyone who has been in the affected NSW areas since June 21 must complete a declaration form, isolate and only leave their residence for approved essential purposes.

Mr Barr has described the risk to the Canberra community as "significant".

"We need everyone to use the Check-In CBR app and to behave and recognise the seriousness of the situation," he said.

Those in breach of the restrictions could face fines of up to $8000.

NSW Police are playing their part in attempting to monitor those travelling south on the Federal Highway with patrol cars at Pheasants Nest.

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