Agriculture Minister Krzysztof Jurgiel said the H5 virus was detected in the swans, which were found dead Thursday in the center of Torun, a northern city about 200 kilometers (120 miles) northwest of Warsaw.

An EU laboratory in Britain was conducting tests on samples from Poland and results were expected within days, Jurgiel said.

Poultry Ordered Indoors

In Brussels, the European Commission said it had been informed by Polish authorities that they were applying a set of EU precautionary measures passed last month for dealing with a bird flu outbreak.

Those measures include ordering poultry indoors within three kilometers (two miles) of the outbreak as well as intensified food controls for any meat leaving the area.

Prime Minister Kazimierz Marcinkiewicz planned to travel to Torun in the afternoon to be briefed on the matter by authorities on the ground and to reassure the city's residents, government spokesman Konrad Ciesiolkiewicz was quoted as saying by the PAP news agency.

The H5N1 strain has killed dozens of humans in the latest outbreak since 2003, mostly in Asia, in addition to devastating poultry stocks. Scientists are concerned that the virus could mutate and pass easily between people, sparking a human flu pandemic.