H5N1 bird flu was found in Sadlowo in the Mazowiecki province, not far from the site where another outbreak was discovered over the weekend.
This is 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.
Marek Sawicki said that the new outbreak was "more of an economic rather than a medical concern," and that the Polish veterinary authorities had set up a safety zone around the site to prevent the spread of the virus.
On Sunday, Poland culled about 110,000 chickens and destroyed over 100,000 eggs in the Mazowiecki province, following confirmation by veterinary authorities that poultry at a farm in Karniszyn had been infected with the deadly H5N1 virus.
Poland's chief veterinary doctor Ewa Lech earlier said that the country could suffer significant economic losses from an outbreak of avian influenza.
Poland is 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 the previous outbreak of bird flu caused wholesale prices for Polish poultry to drop at least 30%.
Meanwhile, last Thursday Russia imposed temporary restrictions on the import of poultry, eggs and all poultry products from Poland following the discovery of bird flu in the country.
Russia's agricultural watchdog Rosselkhoznadzor said the restrictions also applied to bird feed and feed additives, as well as bird-farming equipment that had already been used.
Poland is still subject to a two-year Russian embargo on its meat products, imposed over allegations Poland was supplying poor-quality meat from third countries. Poland has vetoed talks on a new Russia-EU partnership and cooperation agreement in retaliation.
