A second chicken farm in South Korea has been found to contain the H5N1 form of bird flu, officials say.
The new bird flu cases are the first for South Korea in three years
The outbreak occurred at a farm close to where a case was confirmed at the weekend, the first to hit the country in three years.
Quarantine officials are carrying out the slaughter of 236,000 poultry around the first infected farm in Iksan, about 250km (155 miles) south of Seoul.
Dogs, cats and pigs are also being culled in a bid to stem the outbreak.
"The test results have shown that we had a second case of highly-pathogenic H5N1 bird flu," South Korea's agriculture ministry said.
The new case was found at a farm in Hwangdeung district, just 3km (1.9 miles) from where the first outbreak was found, the ministry added.
As with the first farm, livestock within a 500-metre (1,650-foot) radius of the latest outbreak are to be culled to prevent the virus from spreading.
The ministry said the cull may be extended to a radius of 3km from both farms.
The culling of 236,000 poultry and the disposal of some six million eggs began on Sunday.
The movement of livestock around the infected area is being controlled. Local residents have been vaccinated, although there are no reports of anyone infected by the virus.
Some 600 dogs, as well as cats and pigs, are reportedly due to be slaughtered in Iksan.
A city official said dogs bred on farms for consumption would be killed, but another anonymous official told the Associated Press the cull would cover "dogs raised individually in houses".
South Korea killed 5.3 million birds during the last known outbreak of bird flu in 2003.
The H5N1 virus began hitting Asian poultry stocks in 2003, and has killed at least 153 people worldwide.
Most human cases have resulted from contact with infected birds.
Scientists fear the virus could mutate into a form that is more easily transmitted between people, possibly creating a pandemic.