Forty Americans being taken off the quarantined cruise ship Diamond Princess are infected with new coronavirus, a US official says.
They are among 400 people from the US leaving the vessel docked in Japan.
Most are due to depart for the US on two government-chartered aircraft. But those carrying the virus will be admitted to Japanese hospitals.
Meanwhile, China has tightened restrictions on movement in Hubei province, the centre of the outbreak.
The Diamond Princess has been quarantined in Japan's port of Yokohama with some 3,700 passengers and crew on board since 3 February after a man left the ship in Hong Kong and was found to have the virus.
It has the largest cluster of coronavirus cases outside China. The Japanese authorities on Sunday said the number of new cases on board the ship had risen by 70 to 355.
The 40 Americans who are infected will receive medical treatment in Japan, Dr Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases told Face the Nation on CBS.
"Others are going to be evacuated, starting imminently, to Air Force bases in the United States," he said.
"If people on the plane start to develop symptoms, they'll be segregated within the plane."