Two more passengers have reportedly been diagnosed with coronavirus aboard the Princess Diamond cruise ship that is quarantined off the coast of Japan, bringing the total number of cases to 63.



One of the new cases involved is an American, increasing the ship’s total number of U.S. citizens who have fallen ill to nine, USA Today reported Saturday.



A Fox News request to Princess Cruises on the latest numbers was not immediately returned.



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The cruise ship is docked off Yokohama Port, near Tokyo. It was quarantined on Monday when results came back positive for a guest who had gone ashore in Hong Kong on Jan. 25 and visited a local hospital.



"While on the ship, he did not visit the ship’s medical center to report any symptoms or illness," Princess Cruises said in a statement Tuesday. "The hospital reports that he is in stable condition and the family members traveling with him remain symptom-free."



The passenger, who is from Hong Kong, has claimed was unaware of his coronavirus diagnosis until six days after he disembarked in Hong Kong. The man has alleged that health authorities in Hong Kong initially failed to identify the virus through a thermal screening.



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Cruise officials have been working with Japanese health authorities to investigate and contain the matter. Princess Cruises said that the ship would remain under quarantine until Feb. 19, unless there are any other “unforeseen developments.”



Princess Cruises is one of several cruise lines affected by the coronavirus outbreak, many of which have issued various travel restrictions, delays and cancelations.



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The coronavirus, which originated in Wuhan, China, has spread across the globe with more than 34,954 confirmed cases and 725 deaths as of Saturday morning.



Fox News’ Janine Puhak contributed to this report.