After the discovery of a new case of avian influenza in South Korea, around 197,000 chickens at a farm close to the capital city were culled, the government reported.
The government has imposed a 48-hour ban on transporting poultry products in the north of the country.
The affected farm is located in Pocheon, 45 km north of Seoul, and had recorded the deaths of 30 birds since Tuesday, with preliminary tests showing that they were infected with bird flu, said the Ministry of Agriculture, Food and Rural Affairs.
Inquiries were ongoing to determine whether the case involved the same highly pathogenic strain currently affecting the southwest of the country.
The latest case, the first of its kind in the northern province of Gyeonggi, caused alarm among quarantine officials, who have been fighting to contain the expansion of the H5N6 strain in the southwest of the country since November.
In the province of Jeolla, one of the worst affected, the government confirmed that nine farms had been infected by the virulent strain.
About 36,700 birds had been culled in three provinces and disinfection processes were being carried out in farms in the whole region.
After an H5N6 infection was discovered in the area in December, authorities culled 201,000 ducks.
In 2016, South Korea culled more than 30 million birds to contain the worst outbreak of bird flu in the country's history.