Dozens more coronavirus cases confirmed aboard cruise ship_1

A further 40 passengers aboard the quarantined Diamond Princess cruise ship have tested positive for the lethal coronavirus.

A 21-year-old Melbourne woman is reportedly among the new cases, which also include a Japanese quarantine officer.

The quarantine official had been wearing a mask and gloves, and was collecting and processing questionnaires from passengers.

The officer is already in hospital and had self-isolated as a precaution.

Japanese Health Minister Katsunobu Kato announced the surge in confirmed tests of the coronavirus (which has been renamed COVID-19 by the World Health Organisation) on the Diamond Princess on Wednesday.

Japanese broadcaster NHK said 174 people on board the liner – which is moored at Yokohama – were now confirmed to have the deadly disease.

Meanwhile, the Melbourne woman has apparently become the 12th Australian on board the cruise liner to be diagnosed with COVID-19 – although authorities are yet to officially confirm her infection.

Her grandfather, Peter, who did not want to give his surname, said she was taken off the ship with her parents and younger brother and transported to a hospital about two hours from the port.

"My granddaughter Bianca, who is 21 years old, tested positive and now she's in isolation in the hospital and my three other family members are all in isolation wards over there," Peter told Melbourne radio station 3AW on Wednesday.

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More than 3700 passengers, including about 200 Australians, have been stranded on the ship for a week after dozens of people tested positive for COVID-19.

Yardley Wong, who is among those quarantined on board the Diamond Princess, said the latest rise in confirmed cases was making him anxious.

"Anxiety rising. [I] don't know when it will possibly be my turn — or my family," Mr Wong told the ABC.

Some of the Australians on board have described the new cases as "scary", but others said they were remaining positive.

Peter said the Australians had not heard from the federal government since they were quarantined.

"These people are in limbo and no one cares about them," he said.

"That's how it seems because we've had no contact from the government in any way."

Peter said the family had been struggling mentally and physically, as a result of being trapped in their cabins prior to the diagnosis.

"They were locked up in these two little rooms, 3×3 (three metres by three metres) perhaps, without any access to clean air or anything," he said.

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Authorities are yet to confirm the case, while Princess Cruises said 11 Australians aboard were affected.

"We are following guidance from the Japan Ministry of Health on plans for disembarkation protocols to provide medical care for these new cases," it said.

"Since it is early in the quarantine period of 14 days, it was not unexpected that additional cases would be reported involving individuals who were exposed prior to the start of the quarantine."

The quarantine end date remains February 19 unless there are any unforeseen developments.

Princess Cruises has confirmed all guests aboard the cruise will be refunded their fare, including air travel, hotel, ground transportation and other expenses.

-with AAP