THE HAGUE, June 24 (Xinhua) -- Bird flu was discovered at a poultry farm in the central Dutch province of Flevoland, the Ministry of Agriculture said Friday.

It said the virus discovered was a mild variant. The farm's 47,000 chickens were slaughtered to prevent the virus turning into a contagious and deadly variant.

It remains uncertain whether the chickens were infected with the high or low pathologene H7 variant. The low pathologene version can mutate into a high pathologen, which is extremely transmittable.

Poultry from other farms in a zone of three kilometres of the contaminated farm will be tested. A prohibition of transport for poultry, eggs and poultry manure has been set.