Some 1.9 million ducks and geese have already been culled and a further 1.3 million have died in this year's outbreak of the H5N8 virus in France and Agriculture Minister Stéphane Le Foll announced Tuesday that the 600,000 surviving in the Landes will be slaughtered.
It was necessary to act quickly to stop the virus, he said, adding that protection zones, where fowl will not be reintroduced, will be established.
The Landes has been the worst-hit area, with 151 cases, while there were another 119 elsewhere in the south-west.
Millions of euros lost
The foie gras producers' association on Thursday asked the government to beef up the fight against the latest epidemic, which started in November 2016.
It claims that more than 210 million euros has been lost already and that farmers will face further spending when they implement new anti-bird flu rules.
The government has promised to compensate producers for slaughtered fowl but the target will not be announced until April.
France is the world's biggest producer of foie gras and has suffered badly from bird-flu outbreaks.
The French producers' group says that 1,000 farms have been affected across Europe.