TOKYO - A woman in her 80s is the first person infected with the coronavirus to die in Japan, the Health Ministry said on Thursday (Feb 13), though it stressed that it was not clear if the virus had caused her death.

The woman, who lived in Kanagawa prefecture, to the south of Tokyo, was being treated for pneumonia, having first developed symptoms on Jan 22. She was hospitalised on Feb 1.

Health Minister Katsunobu Kato said that it was only during the post-mortem that doctors found that she tested positive for the disease, officially named Covid-19.

"The relationship between the coronavirus and the person's death is still unclear," he said at a late-night briefing to reporters. "Testing was conducted because she was suspected of being infected with the coronavirus. Her positive result was confirmed only after her death."

The elderly woman has no record of any recent overseas travel including to Wuhan, the epicentre of the coronavirus outbreak in China. The authorities are urgently looking into how she contracted the virus.

This is the third coronavirus death outside mainland China, with Hong Kong and the Philippines having earlier reported a death each. In mainland China, the death toll surged to 1,367 on Thursday after authorities changed the way they calculate the figures.

Meanwhile, Japan also confirmed three other new cases on Thursday, bringing its domestic total to 33. Another 218 people have tested positive on board the Diamond Princess cruise liner, which has been quarantined off Yokohama since Feb 5.

The new cases include a taxi driver in his 70s in Tokyo, a company employee in his 20s in Chiba, to the east of the capital, and a surgeon in his 50s in Wakayama, which borders Osaka.

None of them have any record of recent overseas travel, and the diagnoses mark a further spread of the disease in the country after a gap of several days without any locally-transmitted cases.

The Health Ministry said that there is no evidence of a community spread of the virus in Japan, even as it is doing contact tracing of the four newly-confirmed patients, including the elderly woman who died.

The Wakayama man is the first medical doctor to be infected with the coronavirus in Japan. Authorities are looking into whether he got the disease from a patient - and if he might have passed it on to other doctors and patients.

He first developed fever on Jan 31, but returned to work last week after taking medicine to bring down his fever.

Meanwhile, the Tokyo taxi driver is the son-in-law of the woman who died, Japanese media reported.

Even as there were conflicting media reports over whether he had picked up Chinese passengers before he fell ill, his case will likely raise concerns about the spread of the flu-like virus in the world's most populated metropolitan area. This is given the number of people a city taxi driver comes into contact with.

Meanwhile, the tally of people infected with the coronavirus on the Diamond Princess continues to rise, with 218 people having tested positive as of Thursday.

This is nearly 6 per cent of the 3,711 people on the ship manifest, with the cases traced to a Hong Kong man who disembarked the ship on Jan 25.

Five are in serious condition.

The authorities said on Thursday that passengers aged 80 and above who either have pre-existing illnesses, or live in cabins without windows, will be allowed to move off the ship to government-designated lodgings for the rest of the quarantine period, which ends next Wednesday (Feb 19).

"There are some people whose health may deteriorate by staying aboard for an extended period," said Mr Kato earlier on Thursday.

Japanese Prime Minister Shinzo Abe on Thursday pledged to devote 15.3 billion yen (S$193.5 million) in emergency measures to fight the virus, and to ensure that 600 million new masks will be available within a month.

He had earlier vowed to raise the testing capacity for the new coronavirus from 300 cases a day to more than 1,000, also by next week.