TAIYUAN, Jan. 17 -- Bird flu has caused swans to die in a reservoir area of the Yellow River, the country's second longest, authorities confirmed on Saturday.

According to the National Bird Flu Reference Laboratory, the H5N1 virus, a highly contagious strain of bird flu, has caused deaths among swans and other wild ducks in the Sanmenxia Reservoir Area in Sanmenxia City, central China's Henan Province.

The Ministry of Forestry said on Thursday that 93 wild birds had died in the area as of Jan. 14.

In Pinglu Wetland in the neighboring Pinglu County, north China's Shanxi Province, a total of 22 swans, as well as 25 other wild birds, have been found dead on wetland property since Jan. 4, according to local authorities.

The Pinglu Wetland, which forms part of the Sanmenxia Reservoir Area, is a major winter habitat for swans that migrate from Siberia in Russia. More than 10,000 swans flocked to the wetland every winter.

A group of experts have arrived in Sanmenxia City to provide technical support in protecting the precious birds.

The local governments in Sanmenxia City and Pinggu County have taken a variety of measures to prevent a possible spread of the virus, including blocking the entrance and examining people who had close contact with the birds.

No human infection has been reported so far.