SEOUL, South Korea - South Korean quarantine officials are set to slaughter 273,000 poultry after an outbreak of the deadly H5N1 strain of bird flu, the Agriculture Ministry and health officials said Saturday.

The outbreak occurred at a chicken farm in Cheonan, about 60 miles south of Seoul, earlier this week, the fifth such outbreak since November, said Lee Joo-won, a ministry official.

"We plan to start slaughtering 273,000 poultry within a 500-meter radius of the outbreak site and destroying eggs as early as Saturday evening," Lee said.

The ministry also said it will make a decision whether to kill another 386,000 poultry on Sunday while limiting the movement of about 2.16 million chickens and ducks from 90 farms within a six-mile radius of the outbreak.

South Korea culled 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 more than 160 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.

"People can be infected with H5N1 virus at any time but the disease is curable if people take the antiviral drug Tamiflu within 48 hours after the infection," said Kwon Jun-wook, an official at the Korea Centers for Disease Control and Prevention.

Kwon, the KCDC's director of the communicable disease control team, also called for thorough preparations against the deadly H5N1 strain of bird flu.

Earlier this month, South Korean officials said that the deadly H5N1 strain of the virus had been transmitted to a human during a recent outbreak among poultry, but the person showed no symptoms of the disease as the poultry farm worker developed natural immunity to the disease.