German authorities have slaughtered around 10,000 hens after a case of bird flu was confirmed at a poultry farm in the northwestern state of Lower Saxony, the state's agriculture ministry said on Monday.

Germany's animal health body, the Friedrich Loeffler Institute, confirmed the case as high pathogenic H7N7 bird flu.

The virus has been known to infect pigs and horses as well as birds, but the ministry said it could be transmitted to humans only if they come into close contact with infected animals or their products and secretions. H7N7 infections in humans are generally mild and deaths appear to be extremely rare - the Netherlands reported one fatality in 2003.

As a precautionary measure, authorities imposed restrictions within a 3 km radius around the farm, and ordered all hens within a 1 km radius to be culled.

Lower Saxony, a leading poultry production region, reported outbreaks of the H5N8 strain of bird flu in December, as well as cases of the milder, "low pathogenic" form of the H7N7 strain in March and June this year.