Hundreds of fowl in Siberia have died of the same strain of bird flu that has infected humans throughout Asia, the Russian government said Friday.

No human infections have been reported from the Siberian outbreak, Russia's Agriculture Ministry said in the brief statement identifying the virus as avian flu type H5N1.

"That raises the need for undertaking quarantine measures of the widest scope," the statement said. Ministry officials could not be reached for elaboration.

Since 2003, the H5N1 strain has killed at least 57 people in Vietnam, Thailand, Cambodia and Indonesia, which reported its first three human deaths this month.

International health experts repeatedly have warned the bird flu virus could evolve into a highly contagious form passed easily from person to person, sparking a global pandemic. So far, most cases have been traced to contact with sick birds.

The outbreak in Russia's Novosibirsk region in central Siberia apparently started about two weeks ago when large numbers of chicken, geese, ducks and turkeys began dying. Officials say that all dead or infected birds were incinerated, but it was unclear whether that would effectively stop the virus from spreading.

Juan Lubroth, an animal health expert at the Rome-based U.N. Food and Agriculture Organization, said it was still not known how many birds have been exposed. He said the concern was whether birds that appear healthy might have the virus.

Earlier This week, Russia's chief government epidemiologist, Gennady Onishchenko, said the appearance of the virus in Russia could be due to migrating birds that rest on the Siberian region's lakes.

A recent report released by the journal Science said the finding of the H5N1 infection in migrant birds at Qinghai Lake in western China "indicates that this virus has the potential to be a global threat."

The reports echo concerns voiced by the World Health Organization, which urged China to step up its testing of wild geese and gulls. A WHO official estimated that the flu had killed more than 5,000 wild birds in western China.

An Indonesian official sprays disinfectant for bird flu prevention on chickens at a market in Central Java. The virus has lead to the deaths of hundreds of millions of fowl worldwide.