Medical workers gesture to each other through the window in Zhangzhou Municipal Hospital in Zhangzhou, southeast China's Fujian Province, Feb. 2, 2020. Zhangzhou Municipal Hospital is a designated hospital to treat patients infected with the novel coronavirus in the city. It has started receiving patients with its emergency wards since Jan. 26 in a bid to fight against the virus outbreak. (Photo by Xiao Heyong/Xinhua)

At least 61 people on board a cruise ship off Japan have tested positive for the new coronavirus, the government said Friday, as thousands of passengers and crew face a two-week quarantine.

An additional 41 passengers were found to have contracted the virus, which has killed hundreds of people, most of them in China, and infected more than 30,000 on the mainland.

Japanese authorities have so far tested 273 people on board the Diamond Princess, which was quarantined after a former passenger, who disembarked in Hong Kong last month, was diagnosed with the virus.

"The results of the remaining 171 tests came out and 41 tested positive," Health Minister Katsunobu Kato told reporters.

"Today they will be sent to ­hospitals in several prefectures, and we are now preparing for that."

The newly diagnosed include 21 Japanese, as well as Americans, Canadians, Australians, an Argentine and a Briton.

There were more than 3,700 passengers and crew on the ship when it arrived off Japan's coast on Monday evening. It docked in Yokohama on Thursday to resupply for a ­quarantine that could last until February 19.

Twenty people who were earlier diagnosed with the virus have already been removed from the vessel, including one in serious condition, a health ministry official said, without providing further details.

Testing was initially carried out on those who displayed symptoms or had come into close contact with the former passenger diagnosed with the virus.

But Kato suggested testing would now be expanded to those "who are susceptible to illness, including elderly people and those with other ailments, as well as those who had close contact with the people newly diagnosed with the virus."

There were no immediate details on how many people would meet those criteria or when the testing might take place.

Japan has already reported at least 25 cases of coronavirus aside from the infections on board the ship, and evacuated hundreds of citizens from Wuhan, the Chinese city where the virus emerged, including on a fourth flight Friday.

Passengers on the ship have been asked to stay inside their cabins to prevent new infections, and have expressed confusion and frustration about a quarantine expected to last until February 19.

Passengers in windowless inside cabins have been allowed onto open decks only briefly, under strict conditions, including wearing a mask at all times.

"The quarantine officials require that you avoid congregating in large groups and maintain a separation of at least one meter from each other when talking," the ship's captain said in an announcement on Friday morning.