Prime Minister Han Duck-soo on Friday called for vigilance in efforts to contain the outbreak of African swine fever, a day after officials reported this year's second case of the virus, which is deadly to pigs but not harmful to humans.

The second case was confirmed at a pig farm in Yanggu, a county located about 175 kilometers northeast of Seoul, late Thursday, according to the agriculture ministry.

"Along with swift anti-epidemic measures, thorough anti-epidemic management is needed to prevent further spread," Han told a virus response meeting.

Han said health authorities should figure out the cause of the outbreak as soon as possible to block the possibility of further spread.

Han also urged local governments to actively promote guidance that people need to refrain from visiting farms of pigs and related livestock during the Chuseok fall harvest holiday slated for next month.

Thursday's confirmation of the virus outbreak came 85 days after the first case was reported in May, the prime minister's office said. (Yonhap)