Blood from the remains of some 47,000 pigs, which were kept stacked on a truck at a military camp inside the Civilian Control Line in Yeoncheon County bordering North Korea, got into the nearby Imjin River on Sunday during heavy rainfall, the authorities said.

The contamination was visible in the upper reaches of the river, stretching for about 200 meters.

While provincial authorities installed barriers around the area to stem its flow, the contaminated water quickly spread.

In response to concerns that the water source might be contaminated, authorities said there were no threats to public health as the pig remains had undergone antiseptic procedures.

The Ministry of Environment said it would check water supply facilities in the affected regions to make sure drinking water had not been contaminated.

The county official said about 20,000 culled pigs remain piled up where the incident occurred. Since the outbreak of African swine fever, close to 160,000 pigs have been killed in the Yeoncheon region, and their disposal has been stalled due to the large number.

By Kim Arin (arin@heraldcorp.com)