Bird flu has been identified at a poultry farm in Drenthe, taking the total number of birds slaughtered since the outbreak began to well over four million.

The broiler farm, with 200,000 chickens, is the biggest yet to be affected by the bird flu epidemic, which broke out around a year ago. The health ministry said it is closely monitoring the situation at six other farms within a three-kilometre zone of the Nieuw-Weerdinge location.

The current epidemic is the most serious in 20 years and over 70 farms nationwide have been affected so far. The Netherlands has some 1,700 poultry farms, half of which produce eggs.