Italy's health ministry said the virus had been found in 21 dead swans on the island of Sicily and elsewhere in the south of the country.
Greek officials have called on people not to panic after the virus was detected in swans near the northern city of Salonika.
Cases of the disease were also notified in the Bulgarian wetland region of Vidin, close to the Romanian border.
Detection of the virus within the European Union charted the rapid spread of the disease, which in the past week has crossed into Africa for the first time.
There were disturbing signs in Nigeria that the virus is spreading rapidly through poultry stocks and approaching the Niger border.
Two women who tested positive for bird flu have died in Indonesia.
If confirmed, they would be Indonesia's 17th and 18th fatalities.
China has announced its bird flu toll has risen to eight.