SEOUL/JEJU ISLAND -- South Korea's agricultural ministry said Sunday it has confirmed a case of a highly pathogenic avian flu in the southern port city of Busan.

The Ministry of Agriculture, Food and Rural Affairs said it reached the conclusion after conducting detailed tests on a poultry farm with 6,000 birds.

The farm had purchased 650 Korean Ogol Chickens last month from Gunsan in the country's southwestern region. Some of the birds died off suddenly, which caused quarantine officials to check the farm.

The ministry is set to conduct a more comprehensive probe while culling all birds at the infected farm as well as restricting movement in the area to contain further outbreaks.

Up till Sunday, poultry from Gunsan was sold to Busan, Jeju, Paju and Yangsan. The government is currently seeking to find out if birds originating from the city had been shipped to other regions as well.

Park Bong-kyun, the quarantine chief of the ministry, later pinpointed the southern city of Jeongeup as the origin of the avian influenza's breakout.

The virus is believed to have affected Gunsan when chickens sold to a Jeongeup farm were recalled after some of them died, the official said. Reports of dead chickens from Gunsan farm skyrocketed following the recall, he said.

Another official from the ministry said it has confirmed the major destinations of the chickens sold from Gunsan, but will still take more time to locate all the buyers.

South Korea's southern resort island of Jeju also said earlier in the day that it culled some 10,000 chickens and ducks amid concerns over the spread of avian influenza.

Agriculture Minister Kim Jae-soo highlighted efforts to prevent further spread of the flu.

"At this stage, the most important thing is to prevent the avian influenza from proliferation," Kim said in a meeting of officials in Jeju Island. He instructed officials to inform chicken farm owners of the importance of speedy reports of suspicious cases of the flu. (Yonhap)