China has isolated it's nature reserves and sent more than 3 million doses of bird flu vaccine to a remote western province after migratory birds were found dead from the H5N1 strain of bird-flu.

Poultry across far-flung Qinghai province, neighboring Tibet and Xinjiang, had become the "target of a compulsory vaccination campaign", reportedthe China Daily newspaper story.

This is the first report of H5N1 detected in China since last year. "So far there has not been any human or any other poultry incident that has been reported and there are a lot of measures that have been taken in terms of prevention (and) in terms of vaccination," Reuters quoted Noureddin Mona, China representative for the Food and Agriculture Organization.

The WHO urged the administration to intensify the inspection. "In terms of the evolution of the pandemic (threat) if it spreads over a larger area and this does seem like a new area then it is going to be harder to eliminate the virus from the environment," quoted Dick Thompson, the WHO's spokesman in Geneva,"This doesn't change the risk assessment."

The H5N1 strain had killed 37 Vietnamese, 12 Thais and four Cambodians in Asia in late 2003.