South Korea's quarantine authorities are doubling disinfection efforts to stem the nationwide spread of African swine fever as no new confirmed ASF case has been reported in the past five days.

The country's agriculture ministry said Tuesday it will complete the planned purchase of pigs north of Seoul, where most of the deadly animal disease cases were reported.

The latest ASF case was confirmed in Gimpo, northwest of Seoul, on Thursday. Since then, all suspected cases have tested negative.

Since the first outbreak of the highly contagious disease on Sept. 17, the country has confirmed 13 cases of ASF.

So far, all confirmed cases have been reported north of Seoul, with quarantine officials rolling out intensive operations in the affected areas to prevent the virus from reaching other parts of the country.

The ministry earlier began purchasing all pigs outside a 3-kilometer boundary of farms infected with the virus in Paju and Gimpo -- located near the border with North Korea -- for slaughter and safety checks before the meat is released on the market.

Pigs that are not purchased will be slaughtered as a precautionary step, according to the ministry.

South Korea has already completed the culling of around 150,000 pigs within the 3-km radius of 13 infected farms in the region north of Seoul. The figure accounts for more than 1 percent of all pigs being raised in the country.

The virus is not harmful to people, but it is fatal for pigs and has no cure.

South Korean authorities are yet to discover what brought the virus into the country, although military officials found a wild boar carrying the virus in the Demilitarized Zone (DMZ) bordering North Korea last week.

South Korea's military said it will shoot wild boars crossing the DMZ on sight. The disease is spread by contaminated feed or wild animals carrying the virus. (Yonhap)