Workers clad in head-to-toe protective suits and wearing visors and gas masks gassed thousands of ducks in southwestern France on Friday, a day after authorities ordered a massive cull to contain an outbreak of the H5N8 bird flu sweeping Europe.

Over 13 European countries, including Germany, the Netherlands, Denmark, Poland, Hungary and Sweden, have reported bird flu since October.

France, which has the largest poultry flock in the European Union, has reported 89 cases of the virus, a majority of which are in the Gers region in southwest France.

Several culls took place in the Gers region, which is home to most producers of foie gras, made of duck and goose liver.

Some 800,000 birds out of a population of around 18 million in the whole of the southwest will be slaughtered in the coming week.