Health officials across the continent increased surveillance for a strain of the disease that could mutate into one which spreads easily among humans. The so-called Spanish flu outbreakof 1918, which has been linked to the current strain, killed between 20 and 40 million people.
Romania has suffered suspicious bird deaths in seven locations and has slaughtered more than 1,000 animals. Turkey culled 2,000 chickens and turkeys after reporting its first outbreak of avian flu, which is commonly spread by migratory birds, on a farm near the Aegean Sea.
So far there have been no confirmed cases in Europe of the H5N1 strain of the virus, which has killed 65 people and millions of birds in Asia since 2003. Romania is still conducting tests, and the European Commission said that no cases of avian flu had yet been formally confirmed there.
Two years ago, an outbreak in the Netherlands led to the cull of 30 million birds. Health officials there have only recently lifted the most draconian restrictions designed to prevent contact with migrating birds.
In Europe there is growing concern at the lack of preparedness across the continent for a pandemic if the H5N1 strain arrives. Last week the Council of Europe Parliamentary Assembly said there was a "flagrant lack" of vaccines and anti-viral medicines to combat a pandemic. It said that the countries most at risk were facing the pandemic alone, "without the necessary financial resources to buy anti-viral vaccines and medicines to build up adequate stocks".
In Turkey the Hurriyet newspaper said that up to 16,000 animals would be slaughtered and that the affected district of Kiziksa will remain under quarantine for 21 days. Stray dogs in the area were being killed as a precaution.
Officials say the infected turkeys in Kiziksa probably contracted the disease from migratory birds from the Ural mountains heading for a nearby natural park called Bird Paradise.
Hurriyet reported that Mehmet Eksen, owner of the stricken Turkish farm, feared for his own health. The paper quoted him as saying: "I cried when I witnessed the death of my turkeys. I cannot forget those moments ... But now I think of myself and what will happen to my health. I cannot go near my wife and children."
In Brussels, Philip Tod, spokesman for the European Commission, said: " We are in a heightened state of vigilance. We have surveillance measures in place for poultry and wild birds. All member states are carrying out surveillance jointly financed with the EU.
"Member states have been asked to increase border inspections on live birds and poultry and we have instructed them to increase hygiene measures.
"These measures were taken as a response to the spread of avian flue to Siberia and Kazakhstan.
"We are working with the member states to prepare for the eventuality of a flu pandemic and are providing support and co-ordination."
Romania's Agriculture Minister, Gheorghe Flutur, said scientists had so far been unable to isolate the virus in the suspect birds, a fact which implied that the cause of the outbreak was unlikely to be a virulent strain.
Testing is complex because birds that have developed antibodies to avian flu at some point in their lives may not have contracted the disease.
Three birds that tested positive for bird flu on Saturday in the village of Smardan in fact did not die from it. "We reviewed the tests and it [bird flu] was not confirmed in them," Mr Flutur said.
With the situation remaining confused in Romania, the European Commission said it would send experts to Romania today to help to ascertain the situation there.
The Danube delta, on the Black Sea, contains Europe's largest wetlands, and is a major migratory area for wild birds coming from Russia, Scandinavia, Poland and Germany. The birds mainly move to warmer areas in North Africa, including the Nile delta, for winter.
Brussels is urging member states to prepare for the worst-case scenario, and to stockpile antiviral drugs and to generate more vaccines. The European Commission has limited powers, however, as the primary responsibility lies with EU member states.
The World Health Organisation warned last month that bird flu was moving towards a form that could be passed between humans, and the world had no time to waste to prevent a pandemic.