The agriculture ministry said some 8,400 ducks and chickens were culled at a farm in Hwaseong south of Seoul and in the northern city of Dongducheon.

Since December 31, South Korea has culled 5.45 million birds at nearly 250 farms.

Last month South Korea raised its alert against bird flu. It has been hit by avian influenza three times before, with the last outbreak in April 2008.

South Korea is also grappling with its worst outbreak of foot-and-mouth, which has forced more than three million livestock to be culled.

North Korea last week also confirmed an outbreak of the highly contagious animal disease.

A foot-and-mouth outbreak in the North in 2007 prompted Seoul to send experts, medicines and equipment.