South Korea's agricultural ministry said Tuesday it is currently investigating two suspected cases of highly pathogenic avian influenza from local farms, amid growing concerns over the bird flu spreading across the nation.

Authorities have identified yet another suspected case of highly pathogenic bird flu from a duck farm located in Yongin, just south of Seoul, according to the Ministry of Agriculture, Food and Rural Affairs.

The farm was raising 6,000 ducks and 90,000 quails.

On Monday, another suspected case was reported at a chicken farm in Yeoju, 105 kilometers southeast of Seoul.

South Korea has so far reported 18 highly pathogenic bird flu cases from poultry farms, including at a guest ranch, since late November.

The virus has spread at a faster pace in South Jeolla Province, which accounted for six infections. Four were from North Jeolla Province.

The country reported this year's first highly pathogenic avian influenza case from wild birds in late October. A total of 33 cases were confirmed from wild bird habitats across the country.

A group of 20 suspected cases among wild birds are also currently under investigation.

South Korea completed culling around 6.1 million poultry, including 4 million chickens and 1.2 million quails.

Under local law, poultry within a 3-km radius of farms infected with highly pathogenic cases must be destroyed. (Yonhap)