South Korean confirmed the suspect case of a mild strain of bird influenza virus at a duck farm on Thursday, according to South Korean national news agency Yonhap News.

    The Ministry of Agriculture and Forestry was quoted by Yonhap as saying a series of nucleic acid tests found that ducks at the farm in Gwangju, about 330 kilometers southwest to Seoul, were infected with the low-pathogenicity avian influenza virus H5N2.

    It is the first time that the H5N2 virus has been discovered inthe country. Between December 2003 and March 2004, a highly pathogenic H5N1 virus hit South Korean chicken and duck farms, costing the poultry industry as much as 1 trillion won (951 million US dollars).

    Preliminary tests on eggs from the farm had showed the ducks having the less virulent strain of the influenza that does not spread to humans and mutate into the highly pathogenic subtype.

    All 9,000 ducks on the farm were slaughtered and buried Wednesday, while a wide quarantine area has been designated aroundthe farm to prevent a possible spread, the ministry said.

    The highly pathogenic variant is characterized by sudden onset,severe illness and rapid death, with a mortality that can approach100 percent.

    Following news of the bird influenza discovery, Japan imposed an import ban on chicken from South Korea late Wednesday.