A highly pathogenic strain of bird flu has been discovered at a South Korean poultry farm, causing the Ministry of Agriculture, Food and Rural Affairs to impose a 48-hour nationwide ban on the movement of poultry, farm workers and vehicles. The farms, vehicles and shops that sell chickens and ducks will be thoroughly disinfected, Minister Kim Yung-rok said in a briefing, adding that trade in chickens will be prohibited indefinitely. The H5N6 strain was confirmed at a farm with 12,000 ducks some 300 km southwest of Seoul. The government has raised its avian influenza alert to the highest level in an effort to curb the outbreak early. South Korea has suffered from a number of avian flu outbreaks, the worst one lasting nearly eight months last year. It caused the culling of record numbers of birds and a nationwide shortage of eggs. However, no human infections have so far been reported.