PARIS • More than 3.5 million birds across Europe, including the ducks used for France's famed foie gras, have died from avian flu since October in the most far-reaching outbreak on the continent in four years.

New cases of highly contagious strains of H5N8 and H5N1 have been found in at least a dozen countries, according to data from the World Organisation for Animal Health.

The casualties include hundreds of thousands of ducks in France as well as turkeys, chicken and egg-laying hens in Poland, the European Union's top poultry producer.

The flu - often spread by migrating birds - is found most winters, but this season's reports began earlier than normal and likely will continue until March.

"It is really a high-pressure season," said Mr Nan-Dirk Mulder, senior global animal-protein strategist at Rabobank in Utrecht, the Netherlands. "I'm afraid we're still going to see cases for the next two months."

The outbreak has spurred poultry import restrictions by nations including China and South Korea.

Over two million birds have died in Poland, while Germany has reported almost 30 outbreaks. Turkey farms were hit in Hungary and Britain, and Denmark suspended sales of chickens outside the EU.

The EU is the world's third-largest chicken shipper and any lost sales may benefit its rivals, the United States and Brazil.

France - the world's biggest foie gras producer - has found more than 120 outbreaks in the south-west, where most birds are raised to produce the luxury food.

Producers say 600,000 ducks have been culled since last month and hundreds of thousands more are expected to be killed.

Several Asian countries are also grappling with the virus, with South Korea culling nearly six million birds and India reporting cases in four states.

BLOOMBERG