Workers wearing masks and protective clothes have gassed thousands of ducks in south-west France, in a massive cull that was ordered in an attempt to prevent a spread of the H5N8 bird flu virus.

At one farm in the village of Latrille, in the heartland of duck and geese rearing country, 8,000 ducks were taken by hand and put in coloured metal containers where carbon dioxide was piped in to kill them, normally within seconds.

Workers in head-to-toe protective suits, face shields and gas masks, finished the slaughter in a few hours.

France, which has the largest poultry flock in the EU, has reported 95 outbreaks of the virus.

Most of the cull is taking place in and around the Gers area of south-west France, where geese and ducks are reared in vast numbers to make foie gras.

About 800,000 birds out of a population of about 18 million in the south-west are due to be killed in the coming week.

Authorities in the Czech Republic also ordered a cull of thousands of chickens and ducks, as reports of bird flu came in from across Europe.

The Czech veterinary authority said its order would affect several thousand birds from small flocks and 6,000 ducks at a larger farm, all within two miles of Ivančice and Moravský Krumlov.

The operation is part of mass cull of poultry in France, which has reported 95 outbreaks of the H5N8 bird flu virus. Photograph: Bob Edme/AP

A no entry sign at the entrance of a duck farm in Latrille. Photograph: Regis Duvignau/Reuters