Japan may expand its ban on foreign nationals who have recently been to China's Hubei Province to those from other areas in order to stem an outbreak of a deadly coronavirus, Prime Minister Shinzo Abe said Tuesday.

"We are analyzing the data on patients within China to determine which regions have a high risk," Abe told a Lower House committee. "We remain open-minded on what measures to take, including the possibility of expanding the regions" subject to the travel ban.

"The situation is changing by the minute," he said.

The pneumonia-causing virus has killed 426 people and infected nearly 20,500 in China as of Tuesday afternoon, according to the country's health authorities.

Japan has been scrambling to keep the outbreak from spreading on its shores, and on Saturday imposed a ban on foreign nationals who have been to Wuhan, the central Chinese city at the center of the outbreak, and other parts of Hubei province in the last two weeks even if they show no symptoms of being infected with the coronavirus.

Holders of Chinese passports issued in Hubei have also been prohibited from entering the country in principle. A total of 11 people have been turned away at the border as of Monday, immigration authorities said.

Abe made the comments in response to an opposition lawmaker who pointed out that parts of China's Zhejiang province were also put under lockdown as the epidemic has spread.

Meanwhile, 3,700 people remained in quarantine aboard a cruise ship in Yokohama on Tuesday after a passenger who disembarked in Hong Kong tested positive for the coronavirus late last month.

Those on the Diamond Princess with symptoms such as a fever or cough have undergone testing and are awaiting the results.