China has sent three million doses of bird flu vaccine to western Qinghai province after migrating wild geese were found there killed by the virus.
Infected birds could introduce the virus along their migration routes
Poultry across the remote province had become the "target of a compulsory vaccination campaign", the state-run China Daily newspaper reported.
China on Saturday ordered nationwide emergency measures to try to stop the spread of the disease.
The virus has killed at least 53 people in South East Asia since late 2003.
Tests confirmed that 178 geese found dead in Qinghai province had been infected with the H5N1 bird flu virus, China's official media reported.
H5N1 BIRD FLU VIRUS
Principally an avian disease, first seen in humans in Hong Kong, 1997
Almost all human cases thought to be contracted from birds
Isolated cases of human-to-human transmission in Hong Kong and Vietnam, but none confirmed
The agriculture ministry said the dead birds were found in early May on Bird Island, a research centre and wildfowl reserve popular with tourists on the shores of Lake Qinghai.
Some are believed to have migrated from South East Asia, but officials did not give any details.
China's most recent confirmed case of bird flu occurred last July in the east of the country, although there have been no cases in China of humans being infected with the virus.
The H5N1 strain of bird flu has been confirmed in eight South East Asian countries since 2003, including Vietnam, Thailand and Cambodia, where people have died from it.
The World Health Organization has warned of the great potential threat should the virus develop the capacity to spread more easily between humans.
An expert from China's national bird flu reference laboratory, Cui Shangjin, told the official Xinhua news agency that "people need not be too worried" as the controls introduced should be effective.
The emergency measures include banning people from habitats of migratory birds, immunising poultry raised near habitats and routes of migratory birds, and introducing quarantine measures in Qinghai.