Bombay, India ? India and France both confirmed their first outbreak of the deadly strain of bird flu among fowl, and on Sunday health officials and farm workers in western India began slaughtering a half-million birds to check the spread of the disease.

Tens of thousands of chickens have died from bird flu in recent weeks in western India, and people suffering from flu-like symptoms in the region were to be tested for the infection, officials said.

Saturday’s announcement from France and India came as other nations fought to contain outbreaks of the H5N1 strain, which has spread from Asia amid fears of a worldwide flu pandemic if the virus mutates into a form that is easily transmitted between humans. Bird flu has killed at least 91 people – most of them in Asia – since 2003, according to World Health Organization figures.

In western India, officials began slaughtering 500,000 birds in a 1.5-mile radius around the poultry farms in the town of Navapur where the confirmed cases were detected, said Anees Ahmed, the minister for animal husbandry in the state of Maharashtra.

An unknown number of people in the area were reportedly suffering from flu and fever, and scientists were to start testing them today, said Milind Gore, deputy director of the National Institute of Virology in Pune.

An area of 3 to 5 miles around the cordoned region will be under surveillance, and all poultry not killed will be vaccinated against bird flu, the health ministry said in a statement.

Indian chicken farmers were devastated by the announcement. “All of us will have to start again from scratch, and I don’t know how many of us will survive,” Ghulam Vhora, a member of the Navapur Poultry Farmers Assn., said Saturday. “Most farmers cannot believe the news and are hoping the lab tests confirming bird flu are wrong.”

France confirmed its first case of the H5N1 strain in a wild duck found dead in a bird reserve some 20 miles northeast of Lyon, France’s third-largest city, the Agriculture Ministry said. All fowl have been ordered indoors or vaccinated there.