European Union officials believe the disease has entered Macedonia, amid confirmation of infected birds in Romania and Greece.
In a Russian region, south of Moscow, hundreds of birds have died suddenly, prompting fears of a new outbreak of bird flu there.
If confirmed, the discovery in the Tula region, about 125 miles south of Moscow, would signal the first time the deadly virus has appeared in European Russia.
The dead birds in China were found in a breeding facility in Tengjiaying, a village near Hohhot, the capital of the Inner Mongolia region.
The official Xinhua news agency
European Union officials say they are preparing to extend a ban on imports of pet birds and feathers from Siberia.
EU spokesman, Philip Tod, says the EU executive would send experts to Greece to help identify the bird flu strain there.
Health officials say they will hold a simulation exercise of a flu pandemic by year's end to improve preparedness.
