South Korea continued quarantine efforts to prevent a further spread of bird flu Monday, as a 12-hour lockdown went into effect at all poultry farms in three provinces.

The lockdown, also known as stand-still, prohibits the movement of any animal, persons or vehicle from farms, creating conditions for simultaneously sterilizing all infection sources, including seasonal homes to migratory birds.

"The government is working with district governments to simultaneously inspect and sterilize infection sources to prevent a further spread of avian influenza and terminate the disease at an early date," Lee Joon-won, deputy minister of agriculture, food, rural affairs, told a press briefing.

South Korea reported its first outbreak of AI at a duck farm in Gochang, 300 kilometers southwest of Seoul, on Jan. 16.

The H5N8 strain of bird flu has since been identified in 17 other farms, with tests currently under way for 22 other suspected cases.

Alarms were raised over the weekend when suspected cases were reported closer to Seoul despite concentrated efforts to contain the animal virus. A duck farm in Cheonan, only 80 kilometers south of the capital city. The agriculture ministry said it would

consider all possible measures, including a nationwide stand-still, if necessary.

Over 640,000 poultry have already been slaughtered, with some 810,000 others set to be destroyed.

Ministry officials said the H5N8, unlike other strains of bird flu, posed little immediate threat to humans, noting no human infection of the strain has been reported. (Yonhap News)