Thousands of people sharing toilets, pools and buffets – is this the petri dish of the sea?

Australians trapped on the virus-stricken Diamond Princess cruise ship will face a hectic 24 hours if they choose to be evacuated to an unused workers site near Darwin tomorrow.

Most of the 200 Australians on the ship are believed to flagged their interest in Prime Minister Scott Morrison’s offer of evacuation flight, which will leave Japan for Australia on Wednesday.

However, after the flight they’ll face another 14 days of quarantine at Darwin's Howard Springs facility.

Minister for Health, Greg Hunt, said passengers will have to go through multiple screenings within the first 24 hours of the evacuation process.

“The situation is that within the first 24 hours, both prior to uplift, and through the flight home, and then on arrival here, there will be five screenings,” he told reporters today.

“One on the ship, carried out in conjunction between AUSMAT (Australian Medical Assistance Teams) and Japanese authorities, two on the flight, one at RAAF base, and one after they arrive here at Howard Springs.”

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He said the precise time of tomorrow’s flight is yet to be determined but the passengers are expected to arrive in Darwin either Wednesday night or Thursday morning.

Australians who choose not to take the evacuation flight will be barred from returning to Australia for 14 days.

It comes as another 99 coronavirus cases were confirmed on the Diamond Princess overnight, bringing the total number of cases to 454, including 16 Australians.

“I understand that those who were on board will feel very frustrated about this, as well as their family members,” Mr Morrison said of the second fortnight of quarantine.

“I am very frustrated about it. But, our first responsibility is that we have to protect the health and safety of Australians in Australia today.”

Chief medical officer Brendan Murphy said the extra 14 days in quarantine was crucial to stemming the spread of the virus.

“The Australians who have been quarantined over the last 12 days, many of them have done everything that they have been asked to do and they are probably wondering why we are imposing this extra requirement,” he said.

“We are not quite sure why there have been ongoing infections, but given there has been recent cases, we cannot be absolutely sure that any of the currently well people on the ship who are coming home on Wednesday are not carrying the virus.”

Passengers on the cruise ship have vented their frustration, saying they felt they’d been left in the dark and were getting most of their information from the media.

Australian passenger Vera Koslova-Fu told AAP she didn’t want to go to another facility for 14 days after testing negative to coronavirus.

“You need to tell me why I need to have a further 14 days of quarantine if I am tested negative,” she said.

“We just feel like we’re kept in the dark.”

About a dozen Australian medical experts are heading to Japan today to work on the evacuation plan.

The Diamond Princess has been under lockdown off the coast of Yokohama for more than two weeks with around 3700 passengers and crew on-board, including about 200 Australians.

Mr Morrison and cabinet are waiting for an Australian infectious disease expert’s assessment of the situation on-board the ship, The Australian reported.

The Australians on-board must pass a coronavirus test before they can be brought home, and elderly people will be given priority in the evacuation.

Outside China, the ship has had the largest number of cases of the COVID-19 illness caused by the virus that emerged in China late last year.

The Japanese ministry said it now has tested 1723 people on the Diamond Princess. The ship had about 3700 passengers and crew.

Americans on-board the Diamond Princess were being flown to the US on chartered planes on Sunday, while authorities in Canada, South Korea, Hong Kong and Italy have announced flights home for their citizens.

A plan to fly the evacuees to Darwin to join quarantine facilities where 266 others flown from Wuhan are already staying is understood to be in place, according to News Corp.

Meanwhile, 241 Australians who were also evacuated from Hubei province in China and who have been quarantined on Christmas Island were released on Monday.

A second group of quarantined people will be released on Wednesday.

None of those on Christmas Island or at the facility near Darwin have tested positive to the COVID-19 virus.

The preparations come as NSW Health said passengers arriving into Sydney on some cruise ships would be assessed by experts as a precautionary measure.

A risk assessment will be completed for each cruise ship arriving into the Harbour City before it berths and then a decision will be made by health authorities whether to disembark passengers.

Of the 15 coronavirus cases in Australia, six have been cleared and the remaining nine are all stable.