China has discovered a suspected outbreak of the H5N1 bird flu virus among ducks in an outlying district of the southern metropolis of Guangzhou, the Agriculture Ministry said on Saturday.

The ministry said on its Web site that by Thursday, 9,830 ducks had died of the outbreak in Guangzhou's Panyu District.

Initial tests by provincial officials showed that the birds had died of the highly pathogenic H5N1 virus, which can be transmitted to humans, the ministry said.

They had submitted samples to a national laboratory for further testing, it said, adding that authorities had culled nearly 33,000 ducks to contain the outbreak.

With the world's biggest poultry population and millions of backyard birds roaming free, China is at the centre of the fight against bird flu.

Scientists fear the bird flu virus could mutate into a form that could pass easily from person to person, sparking a global pandemic.

There have been 25 human cases, including 16 deaths, from the virus in China and dozens of outbreaks in birds that have led to the culling of millions of fowl.