Romania said on Thursday that it had found bird flu in nine dead hens in a county close to the Danube delta where the virulent form of the virus first emerged.
Avian flu has been found in more than a dozen villages in the Balkan state since October, including in several places outside the delta which is Europe's largest wetland and lies on a major migratory route for wild birds.
"The H5 virus type has been detected in nine hens from Zavoaia village," Florica Durlea, a bird flu specialist at the veterinarian authority, told Reuters.
Officials had said earlier on Thursday they were testing samples taken after suspicious poultry deaths in the village.
The village, home to more than 1,000 families, would be quarantined and domestic birds in the affected area culled, Durlea said.
Since October, three outbreaks have been confirmed as the deadly H5N1 strain which has killed 69 people in Asia. Samples from other outbreaks have been sent to Britain for testing but officials say it is unlikely that the virus is a different one.
Officials say that high temperatures for the time of the year mean the migration period for wild birds will be longer, increasing contamination risks. The Danube delta near the Black Sea is on the migratory route of millions of wild birds.
Romania's neighbour Ukraine said on Thursday the disease recently detected in the Crimea peninsula was H5N1.
Scientists fear H5N1 risks sparking a pandemic in which millions of people could die if it mutates into a form that spreads easily among humans. But so far there is no sign the virus has changed in this way.