South Korea said Wednesday it has confirmed the sixth case of highly pathogenic bird flu from a duck farm, raising concerns over the disease penetrating deeper into the local livestock industry.

Local authorities identified the latest case from Naju, 355 kilometers south of Seoul, according to the Ministry of Agriculture, Food and Rural Affairs. The country has been reporting highly pathogenic cases from different regions, ranging from Gyeonggi Province to South Jeolla Province.

Highly pathogenic avian influenza is contagious and can cause severe illness and even death in poultry.

South Korea reported its first farm-related case in Jeongeup, about 290 kilometers south of Seoul, in late November.

The country is currently looking into another suspected highly pathogenic case from a quail farm in Yeoju, 105 kilometers south of Seoul.Earlier in the day, authorities said they have destroyed around 2.7 million poultry -- 361,000 ducks, 1.5 million chickens and 885,000 quails -- since Nov. 28 to prevent the spread of the bird flu.

Authorities cull poultry within a 3-km radius of infected farms.

Birds at farms with suspected cases are also destroyed.

The country reported its first highly pathogenic case in 32 months in late October in Cheonan, 92 kilometers south of Seoul, from wild birds. Since then, a whopping 19 cases have been found from wild bird habitats across the country.

Health authorities are investigating 17 suspected cases of highly pathogenic bird flu among wild birds as well. (Yonhap)