Japan has been forced to defend its policy amid criticism for the way it handled the situation, with dozens of new infections detected almost daily since the ship arrived in early February. Authorities say the virus is now being transmitted locally, and have asked citizens to avoid crowds and non-essential gatherings.

The new cases on the cruise ship will be sent to specialised hospitals, the ministry said in a statement, without giving further details such as their nationalities. Of those who tested positive, 65 were not yet showing symptoms.

“We have done tests for everyone (on the ship),” Japanese Health Minister Katsunobu Kato told reporters. “Some results have already come out … and for those whose test results are already clear, we are working to prepare disembarkation,” he said.

In a letter sent to passengers, authorities explained that some test results would take time to process and that therefore “we plan the disembarkation to take place from 19 to 21 February”.

“If you and your roommate are both negative and have no fever of respiratory symptoms, you will be able to prepare for disembarkation,” the letter said.

But those who had close contact with anyone who tested positive will have their quarantine reset to the last date.

The crew, some of whom have complained about conditions on board, are also expected to remain to observe another quarantine period after the last passengers leave the ship.

Among the new cases, Indonesia’s foreign minister on Tuesday confirmed three Indonesian crew members on board the Diamond Princess have tested positive for the coronavirus.

“We have obtained information that three of the 78 Indonesian crew members aboard the cruise ship were declared confirmed,” Retno told media in Jakarta.

Two of the workers were taken to a hospital in Chiba, while the third was awaiting hospitalisation as of noon on Tuesday, The Jakarta Post reported.

Indonesia has no known cases of the coronavirus, despite neighbours reporting multiple cases.

Spokesman Yoshihide Suga on Tuesday said the government was “currently conducting preparations so that clinical trials using HIV medication on the novel coronavirus can start as soon as possible”.

Suga said he could not comment on how long it would take for the new medication to be approved.

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Britain on Tuesday became the latest country to offer its citizens a way off the boat, saying it was “working to organise a flight back to the UK” as doubts grow over the effectiveness of the quarantine measures with every spike in positive cases.

Canada, Australia, Hong Kong and South Korea have already said they will evacuate their citizens from the ship, following the lead from the United States, which flew home around 300 Americans on Monday – including more than a dozen who had tested positive.

South Korea on Tuesday said an Air Force plane was due to depart Seoul to pick up five people, including four Koreans and one Japanese spouse.

There are 14 South Koreans on board in total, but the other 10 declined to be evacuated as they live in Japan, Yonhap news agency reported.

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Canada on Tuesday said it had “secured a chartered flight to repatriate Canadians on board the Diamond Princess” but gave no details on when the process would take place.

There were 256 Canadians on board the ship, with 32 so far testing positive for the virus.

“Everyone wants to return home as soon as possible, so considering that feeling, we are making preparations smoothly, so that they can go back to their home,” Kato told reporters.

Also on Tuesday, four Japanese nationals who were aboard the Westerdam – a cruise ship which was earlier refused entry to Japan and four other ports due to suspected cases of infection – arrived at Tokyo’s Haneda airport in the morning, Foreign Minister Toshimitsu Motegi said.

They cleared an initial screening in Cambodia where they disembarked, and were undergoing another test following their arrival in Japan, he said.

Another Japanese national who worked as a crew member on the Westerdam wished to remain with the vessel, Motegi said, adding the ministry would stay in touch and provide necessary help.

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While foreign governments have couched their decision to remove citizens as an attempt to reduce the burden on Japanese authorities, many have interpreted the evacuations as criticism of Tokyo’s handling of the situation.

On Monday, the amateur portion of the Tokyo Marathon, which had been expected to attract some 38,000 runners, was cancelled. Only elite athletes will now be able to take part.

The public celebration for Emperor Naruhito’s birthday has also been scrapped over virus fears.