The Diamond Princess cruise ship with over 3,000 people on board arrives at Yokohama port on Feb 6, 2020. (KAZUHIRO NOGI / AFP)

TOKYO — Another 41 people on a cruise liner off Japan tested positive for coronavirus on Friday, bringing the total confirmed cases to 61, with thousands of passengers confined to cabins as testing continues.

The cruise ship, Diamond Princess, and the roughly 3,700 people aboard have been under two-week quarantine since arriving back at the port of Yokohama, just south of Tokyo, on Monday night, after a man who disembarked in Hong Kong was diagnosed with the virus.

Health Minister Katsunobu Kato told a news conference 21 of the newly found 41 cases were Japanese. Further tests would be conducted if additional passengers on board the ship developed symptoms

The total 61 cases came from a sample of 273 people who had been tested because they were either showing symptoms or had been in close contact with those who did, according to the health ministry.

READ MORE: 20 infected on cruise ship in Japan, 171 await test results

Health Minister Katsunobu Kato told a news conference 21 of the newly found 41 cases were Japanese. Further tests would be conducted if additional passengers on board the ship developed symptoms, he said.

TV footage showed blue and white hoardings put up in the vessel where passengers diagnosed with the virus were being moved out to medical facilities. 

The new patients would be transported to hospitals in Tokyo and neighboring towns, the health ministry said.

The rise in the number of infections has worsened the mood for passengers stuck on the cruise, who were only allowed onto open decks briefly for fresh air.

“A bit more anxious today after announcements of more positives,” one passenger, a 43-year-old Hong Kong resident on the ship with his family, told Reuters.

“I expected about that number. But it’s still a shock to hear it. There must be more who were without symptoms at the last screening who will develop symptoms,” said the man, who declined to be identified.

Ashley Rhodes-Courter, an American whose parents are on the boat, said she hoped US officials would be able to help her parents leave the boat.

“They are all breathing circulated contaminated air so they could be getting everyone infected,” Rhodes-Courter told Reuters.

The virus can be transmitted via droplets from an infected person exhaling, coughing or sneezing, and can also spread via contaminated surfaces such as door handles.

Experts have said it is more easily transmitted than the SARS virus.

With the Tokyo 2020 Summer Olympics less than half a year away, Games organizers have set up a task force to deal with the situation

Separately, Chief Cabinet Secretary Yoshihide Suga said a fourth chartered flight had brought 119 more Japanese nationals from Wuhan.

Three planes last week brought a total of 565 evacuees back to Japan, a handful of whom were confirmed to have the virus.

ALSO READ: 10 test positive for virus on quarantined cruise ship in Japan

The new ship cases take the total number of coronavirus infections in Japan to more than 80, according to Reuters calculations. 

Separating out the cruise line cases helps authorities demonstrate they’ve been able to keep domestic transmissions low, said Ikuo Tsunoda, professor of microbiology at Kindai University.

“Whenever I see the table of the number of patients infected around the world, the top line is always of course China, and now in the past few days, the second country is Japan,” Tsunoda said. “It looks really bad.”

2020 Summer Olympics less than half a year away, Games organizers have set up a task force to deal with the situation.