Large flocks of migratory birds have landed in South Korea, placing authorities and livestock farmers on alert amid the country's rising number of avian influenza(AI) cases.

The Ministry of Environment said Thursday, over one-point-three million birds that could have been infected with highly pathogenic avian influenza have made their way to Korea. 

Some 27 cases have been reported so far this year, prompting authorities to raise the AI alert level to the highest level last month. 

Of the cases, 14 were detected in wild birds while 13 were found at farms. South Jeolla Province saw the highest number of cases.

The ministry urged the public to refrain from visiting the habitats of migratory birds as part of efforts to curb possible transmission to poultry farms.