A criminal investigation will be launched by police into the conduct of Carnival Australia amid the Ruby Princess cruise ship debacle, which saw 2700 passengers get off the ship in Sydney despite passengers showing coronavirus symptoms.

NSW Police Commissioner Mick Fuller confirmed there would be a criminal investigation into who was to blame for allowing the ship - which has also been linked to a cluster in New Zealand - to dock and disembark infected passengers, after what he said was "a significant amount of deaths".

Ten passengers from the Ruby Princess have died since the ship docked in Sydney on March 19, allowing 2700 passengers to disembark despite some onboard having Covid-19 symptoms.

The ship had previously been in New Zealand - before crossing the Tasman, its last stop had been in Napier, but it had also visited four other New Zealand ports. There have been at least 16 New Zealand virus cases linked to the ship - including shore-based workers in Hawke's Bay.

A New Zealand police spokesperson this evening told the Herald they currently did not plan to investigate the cruise ship company.

A Napier couple say they were not told by cruise ship authorities there was an outbreak of Covid-19 onboard the Ruby Princess when they disembarked in Sydney.

The next day, Andrew and June Ranyard started to experience coronavirus symptoms.

After setting off on an 11-day voyage on March 8, the ship was forced to return to Sydney early, from Napier, after a handful of passengers started to feel unwell with respiratory symptoms. The ship had also visited Fiordland, Dunedin, Akaroa and Wellington.

New South Wales authorities have been slammed for the decision to allow the passengers to freely disembark the cruise ship when it docked in Sydney on March 19.

It's considered one of the biggest "disasters" in Australia's fight against the pandemic.

To date, more than 620 passengers have tested positive for Covid-19. The number accounts for 10 per cent of Australia's confirmed cases.

"There are 10 deaths relating from the Ruby," Fuller said at a press conference. "That's a significant amount of deaths for one incident."

Fuller said there was "clear evidence" coronavirus was brought off the ship. He said it is "too early to tell" whether a crime has been committed, and the only way to determine that was through a criminal investigation.

The investigation comes as it has been revealed the NSW government was aware there were passengers onboard showing coronavirus-like symptoms when the ship berthed on March 19, and that they could be tested for the virus and receive results within hours.

Fuller said a criminal or coronial investigation was needed to work out if cruise line company Carnival was transparent in its advice to NSW Health and the Port Authority.

"The key question that remains unanswered is, and a criminal or coronial investigation will need to be conducted, was Carnival crew transparent in contextualising the true patient and crew health conditions relevant to Covid-19," he said.

"The international licence to enter a [port is given] on the assurance from the captain to the authorities that the vessel is free from contagious disease. This all commenced on the 18th with a 000 call from a member of Carnival to New South Wales Ambulance.

"There was a 17-minute conversation about two passengers that required medical assistance from the ship. After that call an ambulance supervisor, concerned in
terms of the terminology around the infectious nature of some of these passengers, escalated the matter. He did an outstanding job. He then contacted New South Wales Police Marine Area Command who also had concerns around the language, given there were several cruise ships either underway or off the New South Wales shores.

"There were a number of phone calls between ambulance, New South Wales Police and the New South Wales Port Authority. And, can I say, the New South Wales Port Authority did an exceptional job in trying to get to the bottom of the facts in relation to this case.
They made contact with the ship on numerous occasions. They stopped the ship from coming into Sydney Harbour without further medical information, they made contact with the operations manager from Carnival.

"And, in each case, they were informed that Covid-19 wasn't an issue on the ship. So from my perspective, there are many unanswered questions and I certainly can't answer those for you today."

Fuller said it was too early to tell if a crime had been committed, but there was "clear evidence" coronavirus was brought off the ship and resulted in deaths.

"There's clear evidence now when it stopped in New Zealand Covid-19 has come off that ship and at least 10 people have died in Australia from Covid-19.

"The only way I can get to the bottom of whether our national biosecurity laws and our state laws were broken is through a criminal investigation."

The Ministry of Health said on Friday that cases linked to the Ruby Princess in Hawke's Bay made it one of ten clusters nationwide.

There were 29 Covid-19 cases in Hawke's Bay, after five new cases were reported last week.

The Australian investigation would not overlook the actions of the NSW Port Authority, or NSW Health, with Commissioner Fuller saying the actions of "every agency" would be examined.

He said police hoped to establish whether Carnival was downplaying the symptoms of ill passengers onboard by "getting the ship's records, the records from the doctors on the ship" and by talking to the thousands of passengers who were on board, as well as NSW Health Minister Brad Hazzard. However, he pointed out that as the minister, Hazzard did not make operational decisions.

"There seems to be absolute discrepancies between the information provided by Carnival and what I would see is the benchmark for the laws that the federal government and the state government put in place in terms of protecting Australians from cruise ships when coronavirus had started," he said.

Fuller also confirmed that a crew member had been removed from the Ruby Princess today for treatment, and that "near 200" crew members were experiencing symptoms.

NSW Police Marine Area Command is now looking to find a place for the ship to berth long-term.

"We are hoping to find a safe port. There's a number of ports and we do need to be mindful if they need medical attention," he said.

Federal Chief Medical Officer Dr Brendan Murphy would not be drawn on the criminal probe, but described the situation surrounding the Ruby Princess as "very unfortunate".

"Like everyone in NSW Health, everyone regrets that it happened," Murphy said.

"Everyone was making the best decision they could on the information they had at the time. Clearly, it was a very regretful situation."

The Ranyards said they had no clue there was an outbreak on the ship when they disembarked, and were only told when they got home.

"The New South Wales Health Board let us off," he said.

There was no testing done to make sure they were safe to release.

"We weren't told by any of the Princess team that there were infections onboard."

Andrew Ranyard felt there was "a lot of wool pulled over people's eyes".

It is understood those who presented with an illness had swabs taken for Covid-19, but other passengers were not informed.

Their symptoms started with "sweats" and quickly moved to fevers, cramps, diarrhoea, chest coughs and migraine-level headaches which have lasted for 10 days.

Andrew Ranyard, 60, said he was "fit as an ox", but the virus has kept him bed-bound until today.

Meanwhile, his wife has had milder symptoms in the past two weeks.

"She's been my nurse, thank Christ. She's crashed now, so she's suffering a little bit at the moment."

New Zealand's Ministry of Health earlier said it was in the process of contacting the 56 New Zealanders who were on the ship, working with Customs and the Ministry for Foreign Affairs and Trade.

The Ranyards already planned to self-isolate as soon as they returned home, and register with Healthline.

They went to a drive-through testing facility after their symptoms showed up and received their positive test results 36 hours later.

Hawke's Bay District Health Board staff started ringing the couple each day to ask them what their temperatures were, give them advice and see if they needed anything.

"All I can say is that the Hawke's Bay DHB has been amazing," Andrew Ranyard said.

The Ranyards ran into issues getting food when they realised grocery delivery was fully booked, but said their neighbours stepped in to do their shopping for them.

Ranyard said he was worried at first, as the virus hit him hard.

"I was worried due to the lack of getting air in the lungs and that feeling that you can't breathe ... you're breathing, but nothing's happening. You want more air and there's nothing there."

He said it was "very scary".

His wife was "partly asthmatic" and he said if the virus "really gets to her chest, she will be in hospital".

"What do I do without her?"

But Ranyard was sure his 67-year-old wife would "pull through".

He said Kiwis needed to take the virus seriously.

"People are saying 'I got it but I got over it within a week'. Good on you, well done, thank goodness for that. But if it gets you, it hits you hard. Self-isolate, follow the rules."

Ranyard said he took his hat off to Prime Minister Jacinda Ardern for the measures she'd announced so far to slow the spread of the virus in New Zealand, but felt the borders should be completely closed.

"We don't want another Italy, Spain or America." - Additional reporting, Melissa Nightingale