Japanese health minister Katsunobu Kato earlier voiced worries that the rising infection count among the nation's general population could mean the virus's spread has entered a new phase.
The number of people infected with the deadly new coronavirus on a quarantined ship off Japan has risen to 355, the country's health minister said Sunday, as the United States, Canada and Hong Kong prepare to repatriate their residents on board.
The figure is a jump of 70 cases from a government tally released Saturday and comes as Katsunobu Kato voiced worries that the rising infection count among the nation's general population could mean the virus's spread has entered a new phase.
"So far, we have conducted tests for 1,219 individuals. Of those, 355 people tested positive, " Kato told a roundtable discussion for public broadcaster NHK on conditions aboard the Diamond Princess cruise ship.
The vessel has been in quarantine since February 5 at the port of Yokohama near Tokyo, and Japan's efforts to control the viral infections on board have prompted international concern.
The ship was carrying more than 3,700 passengers and crew from more than 50 countries and territories when it docked and was placed in isolation, after authorities found a passenger who got off in Hong Kong during the voyage had tested positive for the virus.
Japanese officia ls continued to find new infections among the passengers and crew and rushed them to local hospitals, while others have been told to stay inside their cabins during the 14-day quarantine period set to end Wednesday.
The US was preparing Sunday to evacuate some of its citizens but said those repatriated will go through another two-week quarantine period at home.
An on-board announcement late Sunday said Americans choosing to leave should get ready, according to tweets from passengers.
"Disembarkation will begin at approximately 9 pm (1200 GMT)," the announcement said, askin g the group to place their luggage outside their cabin doors.
Japan's Self-Defence Forces will use about 20 buses to transport the evacuees to Tokyo's Haneda Airport, according to TV Asahi.
"Based on the high number of COVID-19 cases identified on board the Diamond Princess, the Department of Health and Human Services made an assessment that passengers and crew members on board are at high risk of exposure," the US embassy said in a letter to its citizens on the boat.
Hong Kong has also said it will offer its 330 city residents on board the chance to take a charter flight back.
Canada announced a similar decision to repatriate its nationals, while Australia and Taiwan are considering such a move, according to local media reports.
Japan has not been able to test all those on board due to limited supplies of testing kits, facilities and manpower, which are also needed by authorities tracking the spread of the virus on land.
But the health ministry said Saturday that passengers older than 70 are being examined and those testing negative and in good health will be allowed to leave the ship from Wednesday.
Tests on younger passengers were expected to start Sunday and healthy people will be allowed to get off after Wednesday, it said.
Meanwhile, Japan has seen 53 infections across the nation, including a dozen new cases reported on Saturday and 13 cases among more than 760 Japanese nationals and their relatives repatriated from Wuhan, China, the epicentre of the outbreak.
Kato said Japan will boost efforts to encourage people with possible infections to quickly seek medical care.
"If you look at the figures, we are seeing changing situations compared with before," Kato said on the NHK show.
"What we have to think about now is preventing cases from becoming severe and preventing deaths."