More than 100,000 birds have been culled in Poland after an outbreak of bird flu was detected on a hen farm.
The country's Ministry of Agriculture expects the new outbreak will have a significant economic impact on the Polish poultry industry.
Poland is thought to be one of Europe's largest producers of poultry and poultry products, with annual exports to European markets averaging 230,000 metric tons.
The announcement of previous outbreaks of bird flu caused wholesale prices for Polish poultry to drop at least 30 per cent, according to media reports.
The highly pathogenic (H5N1) avian influenza outbreak was detected at a large laying hen farm in Mazowsze Province.
Over 120,000 birds were culled and 100,000 eggs were destroyed by the Veterinary Service.
The exact damage to the economy has not yet been calculated, but earlier indications have not been good.
This is reported to be the fifth case of avian flu registered by Polish veterinary authorities since last week, when the deadly virus was discovered at three turkey farms in central Poland.
A safety zone has been set up around the site to prevent the spread of the virus.
The deadly bird flu virus has hit numerous locations across the bloc this year.
Hungary suffered an attack of the virus in January. Germany and the Czech Republic have also both reported outbreaks of H5N1.
The Czech Republic was hit with its first bird flu case in March 2006. Since then the country has registered another 13 cases of H5N1 infection of swans.
Also this year, Germany confirmed that H5N1 was found in six wild birds found dead near Nuremberg, and then reported a later incident where three wild swans in the east of the country were also infected.
In April 2006 Germany recorded one incidence of the virus on a farm, and had to cull about 21,000 poultry. Germany last reported H5N1 in August last year after officials detected it in a swan at a zoo in Dresden.
In February, an outbreak H5N1 virus on a Suffolk farm in the UK, owned by Bernard Matthews, killed some 2,600 birds with another 159,000 being slaughtered.