Updated

South Korean quarantine officials will slaughter 236,000 poultry after an outbreak of the virulent H5N1 form of bird flu at a chicken farm, the agriculture ministry said Saturday.

The outbreak occurred at a farm in Iksan, about 155 miles south of Seoul, earlier this week, resulting in the deaths of 13,000 chickens — 6,700 a direct result of infection and the rest culled.

Test results confirmed the outbreak was caused by a "highly pathogenic" type of H5N1 virus, the ministry said in a statement.

It said 236,000 poultry within a 1,650-foot radius of the outbreak site would be slaughtered to keep the virus from spreading.

The ministry also said it would limit the movement of about 5 million chickens and ducks from 221 farms within a 1.6 mile radius of the outbreak.

Park Yong-jong, a city official in Iksan, said the culls would begin Sunday morning.

The "highly pathogenic" type of H5N1 can be lethal to poultry but poses little risk to people, said Kwon Jun-wook, an official at the Korea Centers for Disease Control and Prevention.

"People can be infected with the virus if they come into direct contact with dead chickens," said Kwon, the KCDC's director of the communicable disease control team.

Lee Sang-gil, head of the ministry's livestock bureau, said no one has been infected.

"There is no problem so far," Lee said in an interview with AP Television News.

South Korea killed 5.3 million birds during the last known outbreak of bird flu in 2003.

The H5N1 virus began ravaging Asian poultry stocks in late 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 that could kill millions.

On Friday, the ministry said a low-grade strain of bird flu killed 200 chickens in a separate outbreak south of Seoul. The ministry said the strain was neither H5N1 nor the less dangerous H5N2.

It also said officials would take preventive measures, including disinfecting the remaining 19,000 chickens.

The exact cause of the outbreak, which occurred at a chicken farm in Pyeongtaek, about 40 miles south of Seoul, was undetermined, but a ministry official said it was unrelated to the one in Iksan.