PRAGUE, Feb. 17 (Xinhua) -- Thirteen Czech researchers have been exposed to the H5N1 bird flu virus strain through a contaminated vaccine obtained from an Austrian company, a newspaper reported Tuesday.

    The 13 people who had contact with the ferrets were in danger but were not infected with the lethal virus, said Josef Duben, a spokesman for the Czech veterinary authority.

    Duben told the Mlada fronta Dnes (MfD) that the researchers were given an anti-viral vaccine and underwent tests.

    "Fortunately, none of them got infected," Duben said.

    The bird flu virus was being tested positive on ferrets by the Biotest company in Konarovice when the animals began to die.

    "Suddenly the ferrets started dying, so the research stopped onFeb. 6," said Michael Vit, the Czech chief sanitary official.

    Officials said the ferrets had become infected with the lethal bird flu virus and to be euthanized.

    Baxter, the Austrian pharmaceutical company that developed the vaccine, admitted that it mistakenly sent infected material to the Czech Republic.