Spain probes bird flu after hundreds of storks die near Madrid

About 400 storks have been found dead along a river near Madrid of Spain, officials said Tuesday, raising concerns that a highly infectious strain of bird flu may be circulating.

Initial tests detected a low-pathogenic strain of avian influenza in the area, but the "large number" of stork deaths has fueled suspicions of a more virulent variant, the Madrid regional government said in a statement.

Samples have been sent to a laboratory operated by the Agriculture Ministry for further analysis, it added. Strict control measures are already in place, including bans on free-range poultry farming, limits on visits to breeding facilities, restrictions on raising ducks and geese alongside other poultry, and increased oversight of water supplies.