Danish authorities said they too had found a wild bird infected with an aggressive strain of bird flu, but it was not immediately whether it was the deadly H5N1 strain.
If confirmed as H5N1, it would be the first case of the virus in Denmark. The Copenhagen government has not released any details but is expected to do so soon.
Wednesday, the Swedish National Board of Agriculture said tests done at a European Union lab in Weybridge, England, turned out positive.
"The laboratory in Weybridge has now confirmed that it is an H5N1 virus, just as we thought," Berndt Klingeborn, of the National Veterinary Institute, said in a statement.
The result was expected after Swedish authorities announced Feb. 28 that two wild ducks in southeastern Sweden were infected with the H5 subtype of bird flu. Experts said the strain was highly pathogenic, but sent samples to the EU lab for confirmation that it was H5N1.