South Korea is struggling to contain the spread of bird flu since the discovery of a highly pathogenic strain in November.
Since then it has detected outbreaks at 47 different locations and has culled some 15 million poultry.
Seoul’s Ministry of Agriculture, Food and Rural Affairs said birds within a three-kilometre radius of infected farms were being destroyed.
In one of the latest cases, the highly contagious H5N8 strain of bird flu was found on a duck farm in Eumseong, some 130 kilometres south of the capital Seoul.
There was also a suspected case at another farm further south, at Yeongam, with the potential for the destruction of further 20,000 ducks.