Seventeen passengers and one crew member were diagnosed in NSW while eight passengers have been diagnosed interstate, a statement says.

A NSW Health spokesman says all cruise ships from midnight on Sunday will be held in port until any patients highlighted as having respiratory issues are tested for COVID-19.

"NSW Health will go even further beyond the national protocol and its current own state protocols," the statement said on Sunday.

The Ruby Princess had 1148 crew and 2647 passengers on board when it travelled to New Zealand before returning to Sydney on Thursday.

All cases from the cruise ship are in isolation at home or in hospital and all passengers and crew have been notified and asked to self-isolate for 14 days as investigations continue.

NSW Health on Sunday confirmed 97 new COVID-19 cases, bringing the state's tally to 533.

Of those 533 cases, 46 have been contracted locally without an identified source of infection.

Coronavirus has also infected several backpackers near Sydney's famous Bondi Beach, which has been shut down after hundreds ignored urgent public health warnings about social distancing.

"Several new diagnoses of COVID-19 have been made in backpackers in the Bondi area," NSW Health said on Sunday in a statement.

"There were two recent parties that some of the cases attended where the cases may have acquired their infections."

Those two parties were the Boogie Wonderland party at the Bucket List on March 15 and a party at Club 77 on the same date.

A childcare worker from the Smeaton Grange Young Academics Centre has also been infected with COVID-19.

Any children or staff who went to the centre between March 2 and March 16 are being told to self-isolate.

All beaches in Sydney's eastern suburbs were closed on Sunday, including Bondi, Tamarama, Maroubra and Coogee.

The Northern Beaches Council on Sunday afternoon also closed Dee Why, Freshwater, Manly, Long Reef and Palm Beach due to the "high number of people gathering in some areas".

Mayor Michael Regan is urging the public to change their behaviour to ensure health and safety standards are being maintained.

"We are trying to keep our public spaces open but we need the community to support us and follow the federal government rules, otherwise we have no choice but to act to ensure everyone's health and safety," Cr Regan said in a statement on Sunday.

"We are all in this together and every single person has a role to play. I ask everyone to consider the safety of themselves and others by avoiding public places especially ones they know will be busy, today and for the foreseeable future."

Prime Minister Scott Morrison said authorities may need to crack down even harder if people continue to ignore public health warnings.

"What happened at Bondi Beach yesterday was not OK and served as a message to federal and state leaders that too many Australians are not taking these issues seriously enough," he said on Sunday.

"State premiers and chief ministers may have to take far more draconian measures to enforce social distancing.

"The more Australians themselves assist us in this fight against the virus to protect lives and livelihoods, the more and better able we are to ensure that Australia comes out stronger on the other side."

Under regulations introduced to control the spread of the deadly virus, outdoor gatherings of 500 people or more have been banned.

Health Minister Brad Hazzard urged young people to take the COVID-19 threat seriously, saying "the problem is just over the horizon, on the basis of the numbers that we're now seeing".

"It's a serious matter. Save yourself and save your family," Mr Hazzard said on Saturday.

Australian Associated Press