Eighteen of the more than 300 Americans evacuated from the coronavirus-hit cruise ship Diamond Princess docked near Tokyo are confirmed to have been infected, U.S. health authorities said Friday.

An official of the U.S. Centers for Disease Control and Prevention said in a teleconference that the number of confirmed cases is likely to rise as testing continues, since passengers from the ship "are considered at high risk for infection."

Apart from the 18 confirmed cases, there are also 10 passengers who reportedly tested positive for the pneumonia-like illness in Japan prior to repatriation, the CDC said. Test results for these patients have yet to be confirmed in the United States.

More than 750 foreign nationals have already been evacuated by the United States, South Korea, Australia, Hong Kong, Israel and Canada.

The repatriations have taken place amid mounting criticism of the Japanese government's handling of the virus outbreak.

The two-week quarantine period through Wednesday, which was intended to prevent the coronavirus from spreading in Japan, has been criticized for potentially worsening the outbreak on the ship.

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