The latest case of the highly pathogenic bird flu was reported at a farm in Tongyeong, about 330 kilometers southeast of Seoul, according to the Ministry of Agriculture, Food and Rural Affairs.
The farm is raising various poultry, including geese, ducks and chickens.
The previous wave of farm-linked infections ended in March 2018.
South Korean authorities have culled 28.6 million poultry as a preventive measure.
Earlier this week, South Korea decided to ease its intense precautionary measures and cull only poultry within a 1-kilometer radius of infected farms for the next two weeks, compared with the previous guideline of three kilometers.
The government will decide whether to extend the measure depending on the situation.
The price of eggs continued to sharply increase despite the government's efforts to bring imported goods into the market. It jumped 49.4 per cent on-year over the past week.
The consumer price of chicken meat, on the other hand, has been flattening after suffering double-digit growth over the past weeks. Over the period, the average price edged up by a smaller margin of 6.9 per cent. - Bernama