At least nine dead swans have been found on Danish islands in the Baltic Sea, near the German island where two birds were discovered that tested positive for the H5N1 bird flu strain, authorities said Wednesday.
Tests were being conducted on the birds by the Danish Institute for Food and Veterinary Research to establish the cause of death.
On Wednesday, experts from a German medical institute said preliminary tests on samples from two dead swans found Tuesday on the Baltic Sea island of Ruegen were positive for H5N1. They were Germany's first known cases of disease.
Of the birds found dead in Denmark, five were on Falster Island, about 50 kilometers (31 miles) northwest of Ruegen, and four were on Bornholm Island, just south of the southern tip of Sweden.
The Danish Veterinary and Food Administration urged all farmers to keep poultry indoors to prevent their coming into contact with infected migratory birds. A formal ban on keeping fowl outdoors was expected in a few days, it said, reports the AP.