FILE PHOTO: Mulard ducks at a poultry farm in Montsoue, France, January 12, 2017. REUTERS/Regis Duvignau/File Photo

PARIS (Reuters) - Duck farmers in southwestern France resumed operations on Monday with the latest outbreak of bird flu now deemed to be under control after the culling of millions of birds and a six-week halt to production.

France, which has the largest poultry flock in the European Union, is one of the countries that has been the most affected by the H5N8 bird flu virus that has spread through wild birds in most parts of the continent since late last year.

The loss in output of some 12 million ducks this year - including 4.5 million culled and 7.5 million not produced - combined with the additional costs of tackling bird flu outbreaks, will lead to higher foie gras prices this year, producers said. They declined to give precise forecasts.

“Today is an important day as we are allowed to welcome ducklings again on our farms. But it is only a step, it’s not the end of this painful event. There are still many things to do,” Christophe Barrailh, head of foie gras makers group Cifog, told reporters.

First foie gras products from these regions will not be available before late August or early September, he said.

The cost of a second major bird flu crisis in the country in as many years will be around 350 million euros ($391 million) this year, after a 270 million-euro bill in 2016 when farmers in the region had to halt output for several months to avoid a spread of the H5N1 virus, Cifog said.

In addition, farmers will need to invest in new equipment such as cleaning tools and in extra premises to confine ducks when they are most at risk of contracting the virus carried by migrating wild birds.

France’s foie gras exports have slumped in the past two years due to bird flu, as countries such as major importer Japan shut their borders to shipments. Foreign sales fell to 85 million euros in 2016, a level which is expected to be repeated in 2017 but is down from 104 million euros in 2015.

The French farm and food ministry in a statement said the industry should adhere to stricter production rules adopted during the crisis to avoid new contamination by the virus in future.