About 190,000 ducks have been culled in the Netherlands as the authorities try to prevent the spread of bird flu across northern European countries, BBC reported.
The slaughter involved six farms, following the discovery of a virus in the village of Biddinghuizen, some 70km (43 miles) east of Amsterdam.
Outbreaks of the highly contagious H5N8 strain have been reported in Denmark, Sweden, Germany and Finland.
The Dutch authorities have not said which strain is involved.
Officials said they were checking for bird flu at farms within three kilometres of the original site and imposed a ban on transporting poultry products within a 10 kilometres (six mile) radius.
Avian influenza – bird flu – is an infectious disease of poultry and wild birds.
The H5N8 strain first appeared in South Korea in early 2014.
The virus later spread to Japan, North America and Europe, causing outbreaks at poultry farms between autumn 2014 and spring 2015.