South Korean health authorities are conducting tests on a citizen suspected of having contracted swine flu, as the country heightened its health alert following a global outbreak of the deadly disease, Yonhap News Agency reported.
"A South Korean citizen who recently returned from a trip to Mexico has been classified as a possible swine flu patient," the official said, asking not to be identified.
Lee Jong-koo, director of the state-run Korea Center for Disease Control (KCDC), confirmed that three had been tested for possible infection and one is still being tested with the other two found not to have swine flu influenza.
Governments worldwide are struggling to stem the spread of the highly infectious virus, which has reportedly killed nearly 150 people in Mexico alone.
Human cases have also been confirmed in the United States, Canada and some European countries, according to media reports, raising concerns that the virus is spreading at a faster-than-expected pace.
Swine flu is a respiratory disease caused by type A influenza that regularly causes outbreaks mostly among pigs and is transmittable to humans.
Earlier, the World Health Organization (WHO) held an emergency meeting and raised its alert level by one notch to the third highest.
The South Korean government has also tightened quarantine measures for pork imports from Mexico, the U.S. and Canada, while stepping up inspections of tourists who have traveled to affected areas.
In a precautionary effort, the KCDC said Monday that it will double its stockpile of Tamiflu and other influenza drugs. The amount would be enough to treat 5 million people, around 10 percent of the country's population.