SEOUL, South Korea — North Korea has temporarily barred foreign tourists as a protection against the mysterious virus from China that has killed at least nine people and sickened more than 400, a leading tour operator reported on Tuesday.

The operator, Young Pioneer Tours, which specializes in taking tourists from China to North Korea, said on its website that the country was closing its border to foreign ​tourists starting on Wednesday. Practically all foreign tours to North Korea come through China, and the vast majority of tourists are Chinese.

Simon Cockerell, general manager of Koryo Tours, which also takes tourists to North Korea, said his company had been told that “action was being considered” by the North Korean authorities to prevent the spread of the virus. “We have been informed that we will be told more information in the morning,” he said Tuesday night.

State-run media in North Korea, which tightly controls information from the outside world, reported on the Chinese outbreak of the coronavirus Wednesday, though the reports did not mention a tourist ban. A television news program said officials were working with the World Health Organization to keep the virus from spreading to the North, according to the South Korean news agency Yonhap, which monitors North Korean media.