AMSTERDAM (Reuters) - The Dutch government said on Wednesday it had ordered farmers in the Netherlands to keep poultry flocks indoors after wildfowl infected with bird flu were discovered in several European countries.

Dutch authorities were testing several dead birds for the H5N8 subtype of the virus, which is not believed to be dangerous for humans.

Suspect infections have also been reported in Germany, Hungary, Poland, Switzerland and Austria.

Wild migrating birds can transmit bird flu to farmed poultry. Containment measures are being coordinated with German, Austrian and Swiss authorities.

The Netherlands has more than 100 million hens, pigs, cows and sheep on high-intensity farms. The density makes the animals more vulnerable to disease outbreaks.

Since 1997, 40 million hens, cows, goats, pigs and sheep have been slaughtered to contain outbreaks including swine flu, foot-and-mouth and "mad cow" disease.

(Reporting by Anthony Deutsch; Editing by Robin Pomeroy)