China says it will quarantine all those who travelled on a flight from Mexico with a man suffering from swine flu, in a bid to curb the spread of the virus, BBC reported.
The 25-year-old man flew to Hong Kong via Shanghai on Thursday, and was admitted to hospital.
Beijing said it would put his fellow passengers under week-long observation. It also suspended flights from Mexico.
The move came as South Korea confirmed a case of the virus, the second country in North-East Asia to do so.
Globally, 16 countries have now reported swine flu cases. Six countries have confirmed person-to-person transmission.
In cases outside Mexico, where the virus emerged, the effects do not appear to be severe.
In Mexico itself, officials have raised the number of confirmed deaths to 16.
Restaurants, public buildings and businesses have been closed for five days to try to bring the virus under control.
Mayor Marcelo Ebrard said the emergency measures were bringing results, with the numbers "getting better every day".
He said the next 10 days would be critical in determining whether restrictions should remain in place.
Some health experts say the strain of the virus may not be as deadly as first feared.
Dr Anne Schuchat, acting deputy director of America's Centers for Disease Control and Prevention (CDC), said that although experts were concerned about the possibility of severe cases, the majority so far had been "mild, self-limited illness".
The new virus lacked the traits that made the 1918 flu pandemic so deadly, another CDC official said.