The second reported case of bird flu this year is of the same highly pathogenic strain as the first case, the agriculture ministry said Sunday.

Two duck farms in Buan, 280 kilometers south of Seoul, were reported to be infected with avian influenza, and one was confirmed to have the H5N8 strain, the ministry said.

Samples from the other farm are still being tested, it said.

On Friday, the government confirmed the outbreak of H5N8 in Gochang, 296 kilometers south of Seoul, the first outbreak of AI since May 2011. It culled some 21,000 birds at the farm.

"The Gochang case and the Buan case were reported within the interval of a day, but rather than the AI in Gochang spreading to Buan, it is likely that the two places were exposed to the virus at around the same time," said Joo Yi-seok, head of the animal disease control bureau at the Animal and Plant Quarantine Agency.

South Korea is stepping up quarantine measures to stop the spread of bird flu. The quarantine authority has launched an investigation into the possibility that the deadly animal virus might have been caused by migratory birds, and the government has issued an order in South and North Jeolla provinces to temporarily prevent poultry, livestock raisers and their vehicles from leaving the areas on Sunday and Monday.

Prior to the latest series of outbreaks, South Korea was hit by AI four times, with the last cases occurring in 2011 that led to more than 3 million poultry being slaughtered.

In 2008, the government slaughtered 3.45 million birds because of the virus, at a cost of around 32 billion won ($28.4 million). Other outbreaks took place in the winter months of 2003-4 and 2006-7. (Yonhap News)