Delta Air Lines said Wednesday it will reduce flights to South Korea as concern rises about the spread of the new virus beyond China.

Delta said it will suspend flights between Seoul and Minneapolis after Saturday and running through April 30. Delta also said it will reduce flights from Seoul to Atlanta, Detroit and Seattle to five times a week. The airline said last fall that it was operating about 28 flights per week on those routes.

The Atlanta-based airline, the world’s largest by revenue, will also delay the start of new flights between Seoul’s Incheon Airport and Manila. Instead of beginning March 29, the launch has been pushed back to May 1.

Delta, United Airlines and American Airlines have already suspended all flights to and from mainland China and Hong Kong. United said this week that demand for service to China had disappeared, and that March bookings for flights elsewhere in the Asia-Pacific region had plummeted 75 percent since the outbreak.

The number of new cases of the COVID-19 virus reported Tuesday was greater outside China than inside China for the first time, according to the World Health Organization. South Korea has reported more than 1,200 cases and 11 deaths.

Several airlines in Asia and the Middle East have suspended flights to other Asian countries besides China. The list includes Korean Air, Japan Airlines and Philippine Airlines. Singapore Airlines, hurt by weak demand, has suspended flights to several destinations in the U.S. and Europe.

Shares in the U.S. airlines that fly to Asia have been hammered – they have been among the biggest losers during this week’s stock market downturn.