Serbia has confirmed its first case of bird flu in a swan found dead in the region of Sombor close to the Croatian border.
The Ministry of Agriculture said the bird tested positive for the H5 strain of avian influenza and that samples would be sent to a British laboratory to determine whether the dangerous H5N1 was present.
Neighbouring Croatia, Hungary, Bosnia, Bulgaria and Romania have already reported bird flu cases in wild fowl.
Serbian authorities stepped up border controls last month and ordered farmers to keep poultry indoors and under constant veterinary supervision.