South Korea will double its reserve of the antiviral Tamiflu and other influenza drugs as swine flu outbreaks in other countries raise concerns over its spread, a top health official said on Monday.

"We believe that the nation has a sufficient amount of influenza medicine, including Tamiflu and Relenza," KCDC Director Lee Jong-koo told local reporters, adding that the government still plans to increase the stockpile amount to cover up to 5 million people.

Currently, the state-run Korea Center for Disease Control (KCDC) 's reserve of Tamiflu to treat up to 2.5 million people, around 5 percent of the population, local media said.

The decision comes as a new strain of swine flue, which accounts for recent deaths in Mexico, keeps being spotted around the globe.

Human cases have also been confirmed in the United States, Canada, and some other nations also have reported suspected patients.

Swine flu, a respiratory disease caused by type A influenza, is known to cause outbreaks among pigs and to be transmittable to humans.

The South Korean government since Saturday has tightened quarantine measures for pork imports from the United States Canada and Mexico.