WARSAW, Poland (AP) — Prosecutors are investigating allegations that a U.S. medical equipment company offered bribes to hospital officials across the country in order to secure deals, the said Monday.

Dozens of private apartments and offices have been searched in recent months for evidence of allegations that between 2003-06 employees of the Polish branch of Stryker Corp. offered bribes to hospital heads to win tenders worth hundreds of thousands of zlotys, said Leszek Golawski, prosecutor in the southern city of Katowice. He could not say whether the evidence gathered from hospital and Stryker Poland documents could lead to indictments. The case involves some 100 people and 51 hospitals.

There was no immediate comment from Stryker Corp. in Poland.

In a separate case concerning Stryker Poland, a court in Olsztyn earlier this year overturned an indictment and a prison term for a local hospital director a lower court had found guilty of accepting bribes from Stryker. The case will go back to court.

Based in Kalamazoo, Michigan, Stryker is one of the world's biggest medical, reconstructive and surgical technology companies, making equipment and prosthetics.