The suspected case was in Hwaseong, Gyeonggi Province, about 42 kilometers south of the capital, according to the Ministry of Agriculture, Food and Rural Affairs. It would have been the first ASF case to occur south of Seoul, if it tested positive.
So far, all confirmed cases have been reported in northern areas of Gyeonggi Province and Incheon adjacent to the border with North Korea. A suspected case was reported in central South Korea on Sunday but also tested negative.
Since mid-September, South Korea has experienced a total of nine confirmed ASF cases, with five of them being on Ganghwa Island in Incheon.
Although ASF is not harmful to people, it is fatal for pigs and there is no cure currently available, making culling affected pigs the only viable option to prevent the spread of the deadly animal virus.
The ministry said it has culled around 85,000 pigs as of Tuesday morning. The total number of pigs slaughtered or to be culled will reach nearly 98,000, it added.
Quarantine officials have been culling pigs within a 3-kilometer radius of infected farms. As most of the confirmed cases were sited on Ganghwa Island, the ministry plans to slaughter all pigs -- an estimated 38,000 animals -- raised in the area.
The culling of pigs in affected areas beyond Ganghwa has been already completed.
The ministry said it plans to finish the slaughtering as soon as possible, before Typhoon Mitag, which is expected to bring heavy rain and strong winds, hits the nation. A heavy rain alert has been issued in southern parts of the country.
Rain may hinder quarantine operations as it can wash away disinfectants already spread on the ground near pig farms and related facilities.
All parts of Gyeonggi Province and Incheon, along with neighboring Gangwon Province, have been designated as tightly controlled zones subject to more stringent disinfection operations and checkups.
Vehicles involved in the livestock industry in northern Gyeonggi Province are also banned from traveling outside of the areas. (Yonhap)