The swans were initially subjected to a quick test on Friday. Following suspicion that they were infected with the H5 virus, the remaining swans from their flock were shot dead. Four were transported to the Veterinary Office in Sarajevo for additional tests, while the area in which they were found was disinfected and isolated within a three kilometre radius.
Local authorities listed households in the area and the fowl in their possession.
Swan samples have been sent to the EU laboratory in Weybridge, Great Britain, for additional tests.