South Korea Friday confirmed an outbreak of bird flu at two poultry farms in the central and southwestern parts of the country.

Suspected cases reported on Dec. 29 from a duck farm in Cheonan, South Chungcheong Province, and a chicken farm in Iksan, North Jeolla Province, tested positive for the H5N1 bird flu virus, the Ministry for Food, Agriculture, Forestry and Fisheries said.

Both farms have been placed under quarantine with authorities moving to cull and bury their ducks and chickens to prevent the spread of the disease. The ministry has raised the alert level for the disease to "caution."

The country confirmed three cases of bird flu from migratory birds earlier in the month. In August 2008, South Korea declared itself free of bird flu after the country suffered its worst outbreak of the disease with nearly 8.5 million birds culled.