Japan has announced its first death from the coronavirus outbreak, hours after confirming 44 more cases on a cruise ship quarantined near Tokyo, as fears of the spreading disease mount in the country.

The health minister, Katsunobu Kato, said the first fatality was a woman in her 80s who had been in hospital since 1 February, when she was diagnosed with pneumonia.

Her confirmed diagnosis came after her death, he said. The woman, a resident of Kanagawa prefecture near Tokyo, was the mother-in-law of a taxi driver who also became a newly confirmed case, Japanese media reported. Health ministry officials declined to officially confirm a relationship at the request of the family.

Authorities also confirmed two more cases: a doctor in his 50s who works at a hospital in western Japan and a man in his 20s who lives in Chiba, near Tokyo. None had a record of travelling abroad in recent weeks or contacts with Chinese nationals – a possible sign that the virus is spreading inside the country.

Earlier in the day, Kato said there were 44 more cases on the Diamond Princess, which is still carrying nearly 3,500 passengers and crew members. The cruise ship now has 218 people infected with the virus aboard out of 713 tested since it entered the port of Yokohama on 3 February, the largest cluster of infections outside China.

There was better news, however, for passengers aboard the Westerdam, a cruise ship carrying 2,200 passengers and crew that docked in Sihanoukville, Cambodia, on Thursday after being turned away by several other ports in Asia because of fear of the virus.

Cambodian authorities were carrying out health checks before allowing passengers to leave the ship. Disembarkation is due on Friday.

“We’ve had so many near moments we thought we were going home only to be turned away,” Angela Jones, a US tourist on board, told Reuters. “This morning, just seeing land was such a breathtaking moment.”

No cases of the virus have been detected on the ship, but about 20 passengers have reported stomachaches or fever, Cambodian health officials said. The ship’s health staff considered them to be normal illnesses, but the affected passengers were being isolated from others, a health ministry spokeswoman said.

The World Health Organization’s director-general, Tedros Adhanom Ghebreyesus, praised the Cambodian government’s decision. “This is an example of international solidarity we have been consistently calling for,” Tedros said. “Outbreaks can bring out the best and the worst in people.”

Japanese authorities, meanwhile, said they would allow some older passengers to leave the Diamond Princess to spend the remainder of their 14-day quarantine in government-designated accommodation.

“If they test negative, those who wish to disembark can go and live in a lodging facility that the government will prepare,” Kato said. We will make every effort to ensure the safety and peace of mind of the people.”

Priority is being given to passengers aged 80 or older who are staying in a cabin without a balcony, and those in a similar age range with chronic health conditions.

About 80% of the ship’s passengers are aged 60 or over, with 215 in their 80s and 11 in their 90s, according to Japanese media.

The Diamond Princess’s passengers and crew were originally to be quarantined on board until 19 February.

The ship – home to the single largest cluster of infected people outside China – has been moored off Yokohama, near Tokyo, since 3 February after it emerged that a former passenger who disembarked in Hong Kong last month had tested positive for the virus.

Reuters contributed to this report