Preliminary tests on fowl from a region south of Moscow where hundreds of birds died suddenly detected a deadly strain of bird flu (search), Russia said Wednesday, bolstering signs that the dreaded virus might be spreading across Siberia to the Mediterranean.

The United Nations' Food and Agriculture Organization (search) warned of a marked increase in chances that bird flu would move to the Middle East and vulnerable Africa as well, while the European Union announced plans for an exercise simulating a human flu pandemic to improve readiness in case the bird virus mutates to form a strain transmissible among people.

In Asia, crucible of the virus, China on Wednesday reported a fresh outbreak of the lethal H5N1 flu strain (search). The official Xinhua news agency said 2,600 birds in the northern grasslands had died of the disease. It did not give details on when the birds were found, and sought to reassure the public that the outbreak was contained.

The H5N1 strain was detected in Siberia in July. Migratory birds flying over the region from elsewhere in Asia were blamed for the outbreak, and the virus had been registered in six districts in Siberia and the Urals region.

Preliminary genetic tests now have found an H5N1 flu virus in samples of birds taken from a village south of Moscow, the Russian Agriculture Ministry said. Further tests are needed to confirm the finding and determine whether the H5N1 strain is the same one that has devastated flocks in Asia since 2003.

If so, it would mark the first appearance of the virus in European Russia, west of the Ural Mountains.

Officials said 220 of 3,000 domestic birds in the village of Yandovka had died. Birds on the six affected farms were being destroyed, and local officials have decided to kill all poultry in the village. In addition, a quarantine was established around Yandovka. Villagers were prohibited from leaving except in emergencies.

More than 200,000 people in the region were given standard flu vaccinations, the ITAR-Tass news agency said. Such shots are given to prevent normal flu so that if the person gets infected with the bird virus, there is no human flu strain inside the body to mix with and create a dangerous hybrid.

The H5N1 strain of bird flu has killed 60 people in Asia, but no one in Russia has been diagnosed with it, officials said. Most human cases have been traced to direct contact with infected birds, but scientists fear the virus will mutate into a form that can spread from person to person, possibly killing millions.

In Hungary, officials announced Wednesday that preliminary experiments with an H5N1 vaccine indicate it works. Health Minister Jenoe Racz said he and dozens of others were inoculated three weeks ago and tests showed that antibodies to the virus had appeared in his blood.

"The results are preliminary, but I can say with 99.9 percent certainty that the vaccine works," he said.

However, the World Health Organization said it was unaware of the details of the Hungarian findings and was unable to comment on their validity or whether the vaccine — even if it works — would be viable.

Scientists in the United States already have reported positive results from tests on their own H5N1 vaccine, but so far have not been able to make the vaccine a practical option because it uses too much of a scarce ingredient and requires two doses to work.

The EU, meanwhile, was trying to assess whether the H5N1 strain of bird flu had spread into Macedonia and Greece. H5N1 already has been confirmed in two villages in Romania and in Turkey.

Global health experts are keeping a close eye on bird flu because they fear the Asian H5N1 strain could mutate and trigger a human flu pandemic.

Asia is considered at greatest risk, but the U.N. Food and Agriculture Organization expressed fear that Africa was poorly prepared to respond to a bird flu outbreak.

"One of our major concerns is now the potential spread of avian influenza through migratory birds to northern and eastern Africa," said Joseph Domenech, the FAO's chief veterinary officer.