Hong Kong ? The global spread of the mysterious flu-like illness that has killed 10 people in the past three weeks appears to have started with a guest in a tourist hotel here.

Hong Kong health officials said Thursday that other guests who caught the disease then carried it to a Hong Kong hospital, Vietnam, Singapore and Canada. Three of the seven people who stayed on the ninth floor of the Metropole Hotel died from severe acute respiratory syndrome.

There are now 306 people sick with the disease, according to the World Health Organization. The vast majority of the victims are in Asia, and about half of them are in Hong Kong. There are 13 suspected cases in the United States.

The cause of the illness remains unknown, but experts believe the most likely explanation is a new virus. There is no known treatment.

Hong Kong health officials have traced most of Hong Kong’s cases to a professor from China’s Guangdong province who stayed at the Metropole Hotel on Feb. 21-22. He died March 4.

His case bolsters the belief that the outbreak is linked to one that began last November in the southern part of Guangdong, where 300 people were sickened and five died.

The WHO said Friday that it was sending a team to Beijing to investigate whether the fatal disease outbreak is linked to the flu-like illness.

The Metropole, a bland-looking, rectangular building, is located in a residential district of Hong Kong’s Kowloon peninsula. It is a short bus ride away from the main tourist area of Tsim Sha Tsui.

During the two days the infected Chinese professor stayed on the ninth floor, three women from Singapore were guests on the same floor. After they returned home, they became ill. Singapore’s Health Ministry said all 34 Singapore SARS patients had been in contact with the three women.

An American businessman from Shanghai also stayed on the ninth floor of the Metropole before flying on to Vietnam and falling ill, officials said.

“His name was Johnny Chen,” said Hoang Thuy Long, director of Vietnam’s National Institute of Hygiene and Epidemics. “When Mr. Johnny Chen came to Vietnam, he was actually in an incubation period.”

Two days after his arrival, he was hospitalized at the Hanoi French Hospital but asked to be moved to a hospital in Hong Kong where he died.

A third Metropole guest during that time was a 78-year-old woman from Toronto. She returned home where she infected her grown son. Both died.

In addition, a Hong Kong man visited a friend on the ninth floor while the professor was there, health authorities said.