China has had no confirmed human infections in its latest round of outbreaks. But it has imposed increasingly strict measures following warnings that a human case was inevitable if China could not stop outbreaks among its 5.2 billion chickens, ducks and other poultry.
Experts are especially worried about China because of the vast scale of its poultry industry and because three major migration routes for wild birds pass over it. Scientists fear wild birds might carry the virus across borders.
Specialists worry that the H5N1 virus could mutate into a strain that could spread from person to person, setting off the feared pandemic. The virus has killed at least 62 people across Southeast Asia.
In Liaoning Province, northeast of Beijing, authorities have destroyed poultry in 15 villages near the site of an outbreak that killed 8,940 chickens, the Xinhua news agency said.
The culling was unusually large by Chinese standards, but Xinhua said it was carried out because of rules requiring the destruction of all birds within three kilometers, or two miles, of an infection site.
Armed police and health workers in protective suits were guarding the villages.
In Beijing, officials closed live poultry markets and vaccinated 20 million birds as a precaution, although the city has no suspected bird flu cases, said Liu Yaping, deputy director general of the Chinese capital's Agriculture Bureau.
Health workers were patrolling zoos, lakes and parks looking for sick or dead birds, she said at a news conference.
Authorities in Beijing were confiscating chickens and ducks from private homes. They said the capital, whose territory includes large sections of countryside, had a total of 24 million chickens, ducks and other poultry. They did not say how many were in private homes.