The European Union has said the type of bird flu recently found in Turkey is the virulent strain that is dangerous to humans.
The EU Health and Consumer Protection chief, Markos Kyprianou, made the announcement at a news conference in Brussels.
It is the first official confirmation that the potentially lethal virus, which has killed more than 60 people in Asia since 2003, has reached south eastern Europe.
Imports of chickens and bird feathers from Turkey were suspended earlier this week.
Health officials have been warning that the virus may mutate and result in a global pandemic in which millions of people could die.
The EU has also confirmed that cases of bird flu have been found in Romania, reversing an earlier assessment that no traces had been found.
The European Commission has announced that it is banning imports of live birds, poultry meat and feathers from Romania.
The Romania Agriculture Minister, Gyorgy Flutor, said further testing would be needed to check if the strain is the more serious H5N1 variety.
The head of the Irish National Disease Surveillance Centre, Dr Darina O'Flanagan, has said precautionary plans have been drawn up to cope with an outbreak of avian influenza here.
She said there was also a stockpile of anti-viral drugs in place.
Dr O'Flanagan said that while there were concerns about the spread of the virus, it was important not to scare the public unnecessarily.