Local authorities were ordered to watch wild birds for signs of disease and impose quarantines if necessary, the official Xinhua News Agency reported on Saturday. It said farms near migration routes were ordered to immunize their birds, while the public was warned to "stop contact with poultry."

The order came hours after the Agriculture Ministry announced that migratory birds found dead May 4 in the western province of Qinghai were killed by the deadly H5N1 strain of the virus. Xinhua said some came from Southeast Asia but it didn't say what species they were.

The ministry "asked the whole country to pay keen attention to the new confirmed cases of migratory birds and to take effective measures to curb possibly spreading the epidemic," Xinhua said.

It said the public "should not be too worried" but said "everyone in the country should enhance monitoring for the epidemic and improve their early warning system."

The regional death toll in the latest bird flu outbreak rose to 53 this week when another fatality was reported in Vietnam.

The World Health Organization warned Thursday that the virus poses a great potential threat to humans if it develops the ability to spread easily from person to person. There is no evidence so far of such a change and most cases have been traced to contact with sick birds.

The dead birds were found in Niannaisuoma, a village near the city of Guangcha in Qinghai, Xinhua reported.

"The disease did not spread to human kind or fowl," Xinhua said. It didn't say how many birds died or give other details.

A report on the Web site of the newspaper Life Daily said 178 birds were found dead on May 4 at Bird Island in the lake, a major research center for migratory water fowl.

China's most recent known case of bird flu occurred last July in the eastern province of Anhui.