A wild goose found dead in northwestern China has tested positive for the deadly H5N1 strain of bird flu in a region known as a stopping point for migrating birds, the government said Monday.

China's national bird flu laboratory on Saturday confirmed the diagnosis of the goose found in Qinghai province, the Xinhua News Agency said on its Web site, citing the Agriculture Department.

Qinghai veterinary authorities sterilized an area where the dead bird was found and stepped up monitoring of migratory birds, Xinhua said. The virus has so far not surfaced in domestic poultry in the area, the agency said.

Qinghai is a known transit point for migratory birds, and the virus killed thousands of bar-headed geese at a nature reserve in the province in mid-2005, raising fears that the virus was on the move, jumping among hosts in the wild

Researchers believe that wild birds from that region may have carried the virus along migratory paths into Russia and elsewhere. The H5N1 virus later found in two human cases in Turkey, which were fatal, was virtually identical to the versions isolated in Qinghai, the World Health Organization said.

The H5N1 virus has spread to people in isolated cases in several countries, killing 113 people worldwide, mostly after they handled infected poultry, WHO said.

Experts fear that the H5N1 virus may mutate into a form easily passed between humans, sparking the world's next deadly pandemic.