WARSAW, Poland, July 3 (UPI) -- Twenty-one homeless individuals in Poland have died after being given an unproven bird-flu virus vaccine, authorities have charged.

Prosecutors have accused three doctors and six nurses of misleading the homeless individuals by telling them they were being given a new influenza vaccine rather than a vaccine for the H5N1 bird-flu virus, The Daily Telegraph said Thursday.

Polish Health Minister Ewa Kopacz has condemned the alleged testing and called for a permanent ban on all involved personnel from future health treatment.

"It is in the interests of all doctors that those who are responsible for this are punished," Kopacz said of last year's testing efforts.

Medical personnel involved with the vaccine trial have denied the allegations, saying the homeless participants knew the type of vaccine they were being paid to take.

The Telegraph said no definitive link has been found between the unproven bird-flu vaccine and the deaths of the homeless.