"That particular lady and this 50-year-old gentleman both attended last Saturday night, independently, a hotel. That hotel is the Crossroads Hotel at Casula."

The carpark at the hotel will have a pop-up testing clinic in place on Friday afternoon.

"If you have any symptoms at all, please get along [to the clinic]," Mr Hazzard said.

The Health Minister said the "troubling" second case was a man in his 20s who had tested positive in the Sutherland area after driving up with a caravan from the Melbourne area.

"At this point, because it is so early, I won't be saying much more," Mr Hazzard said.

"I thank him for coming forward - that is excellent that he came forward, and I encourage others in a similar situation [who] may have come from Victoria or Melbourne particularly to make sure you are on high alert because we in New South Wales are on high alert.

"We want you to get tested — and it is crucial you do — because otherwise you will be the instrument of seeding or one of the possible instruments of seeding here in New South Wales."

Tests misplaced

Meanwhile, 77 swabs from community tests in the Balmain and Rozelle area had gone missing, with Mr Hazzard urging those people who been tested to come forward and get re-tested.

The Balmain and Rozelle area was on high alert last week after a man in Melbourne flew to Sydney and tested positive after working for two days at Balmain Woolworths.

"Those 77 [tests] have been misplaced in the rush to get so many tests done so quickly, but they also ask for you to come back and get retested, and I would obviously ask for that as well," Mr Hazzard said. "Please come back; on behalf of New South Wales pathology, I'm sorry about that.

"But I think everybody understands this is like a war. There is a lot happening every day, a lot of people under massive pressure. I won't point the finger at anybody.

"Obviously, from time to time, human error will occur. That's normal, it's a human system. A human or humans made a mistake and that's all I'm going to say, except to say I'm not condemning them.

"I'm asking to continue to work the enormous hours they've been working and thank them for the work they have done."

The Health Minister went on to say that anyone who has travelled up from Victoria should head home if possible.

"I would ask you at this point to consider packing up your caravan, packing up your tent or what else you have, and head home to Victoria," he said.

"Your government has put in place very strict guidelines and rules.

"It is not helpful to be out of that environment if you were in that environment."

NSW Chief Health Officer Kerry Chant said the man in the caravan made the trip very quickly and had minimal contact on the way to Sydney.

"It is just the person he is with [who is] in the caravan and one or two other contacts that we are now exploring," Dr Chant said.

Mr Hazzard didn't close the door on the state only being open to returning NSW residents going forward.

"We take health advice from the government, but we also have to make decisions in the best interests of the community," he said.

"It's not appropriate we make any further announcements today."

Mr Hazzard said the NSW government was particularly conscious of the challenges Victorians, and Melburnians in particular, are facing.

"Certainly, we want to see the citizens of Melbourne and Victoria comply with their state laws and our laws. Effectively, they just shouldn't be coming here."

It comes as national cabinet agreed to cut the number of international arrivals by just over half across all airports to ensure the risk of COVID-19 infections from the hotel quarantine system can be properly managed.

The Prime Minister also announced a nationwide review of hotel quarantine, to be run by former secretary of the federal Health Department, Jane Halton, who sits on the COVID-19 co-ordination commission.

Victoria recorded 288 new coronavirus cases on Friday, marking the biggest daily increase in infections since the pandemic began and a triple-digit rise for the fifth consecutive day.

The southern state is experiencing a wave of coronavirus infections linked to international arrivals quarantining in hotels in Melbourne, and the city is not currently receiving any inbound international flights. The state is also conducting its own review of the bungled quarantine system.