Ukraine on Sunday began combating what appeared to be the biggest outbreak yet in Europe of the deadly strain of bird flu, after more than 2,000 domestic birds died in a remote region of the Crimean peninsula.

President Viktor Yushchenko declared a state of emergency in five villages on Saturday after the agriculture ministry said it had identified the H5 subtype of bird flu virus. Officials enforced a quarantine and began culling and burning the villages’ birds on Sunday.

But the government’s failure to notice the outbreak earlier is likely to heighten concerns across Europe about Ukraine’s ability to deal with the bird flu problem. Ukrainian villagers who keep birds in their gardens are at particular risk, because they regularly handle birds that may have come into contact with the migratory wild birds that spread the virus.

Confirmation that the outbreak was caused by the H5N1 strain that can kill humans was awaiting the results of tests in Britain and Italy. But officials left little doubt that they were dealing with the same deadly strain that has shown up in Romania and other parts of south-east Europe.

Olexander Baranivsky, agriculture minister, told a press conference he was alerted on Friday after the villages saw up to 20 per cent of their birds die overnight. “Birds are dying from [the virus] in no more than two to eight hours,” he said.

Mr Baranivsky’s ministry has insisted it is keeping careful guard against bird flu by regularly testing wild and domestic birds around the country and making sure the issue gets ample coverage in national and local media.

But villagers told television reporters they were mystified by the disease that had been killing their birds for more than a month. Their stories indicated the disease had started spreading around the same time as the first known outbreak of bird flu in Europe, in Romania’s Danube delta region in October.

The villagers said they had been eating healthy birds and throwing diseased ones on the village dump, where the carcasses were scavenged by stray dogs.

The affected villages are near Lake Sivash, a vast, marshy lagoon next to the Azov Sea where migratory birds stop over each spring and autumn on their way between Russia and Africa or the Middle East.

Romania said at the weekend it was dealing with what appeared to be a new H5N1 outbreak in the country’s south-east, its first outside the Danube delta.

So far no people in Europe have contracted the H5N1 virus, but it has killed 69 in Asia, including one in Indonesia confirmed on Sunday. Health officials believe people generally are not at risk unless they handle birds, but experts worry that a mutation could enable the virus to spread from human to human and thus cause a worldwide epidemic.