The ship, the Diamond Princess, with 2,666 passengers and 1,045 crew aboard has been kept in quarantine at anchor off a pier in Yokohama after a disembarked 80-year-old passenger from Hong Kong was found to be infected with the pneumonia-causing virus.

Of the passengers and crew, 120 who have symptoms including cough and fever and 153 who had close contact with the infected passenger were tested for the virus, the Health, Labor and Welfare Ministry said.

Results for 31 people came back, and 10 in their 50s to 80s including three Japanese nationals were found to be infected and sent to a hospital. None are showing severe symptoms, and some have no symptoms at all, it said.

The government is asking all passengers and crew, who hail from 56 countries and regions, to stay on the ship for 14 days from Wednesday as it continues screening.

The elderly and those with pre-existing conditions will be tested for the virus as they tend to be worst affected if infected, the ministry said.

"We will take appropriate measures to prevent the spread of infections while giving full attention to the health of the passengers and crew," said health minister Katsunobu Kato at a press conference.

Passengers were told the vessel will dock later Wednesday to restock food and other supplies, according to one aboard the ship.

The virus-infected man from Hong Kong flew to Tokyo in mid-January and boarded the cruise ship in Yokohama on Jan. 20. He disembarked in Hong Kong on Jan. 25.

As of Wednesday, more than 24,000 people are infected on mainland China, with the death toll rising to 490, according to the country's health authorities.

The number of foreigners arriving in Japan on cruise ships has been on the rise in recent years, with those from China hitting 1.74 million in 2019, making up about 80 percent of the total 2.15 million, according to the transport ministry.

The total figure has increased 12-fold from the level in 2013, when the ministry started taking records.

After departing Yokohama on Jan. 20, the Princess Diamond stopped at Kagoshima in southwestern Japan two days later before arriving in Hong Kong on Jan. 25.

It then traveled to Vietnam and Taiwan before calling at Naha, Okinawa Prefecture, on Saturday and then coming back to Yokohama Monday night, according to its operator Carnival Japan Inc.

The ship passed quarantine in Naha but the ministry decided to redo it following the discovery that the Hong Kong man had been infected with the coronavirus.

Thirteen people disembarked in Naha, but none has shown symptoms, and they had all left the southernmost island prefecture of Okinawa by Tuesday, according to the ministry.