Italian police say they have arrested nine cardiologists accused of performing unauthorized experimental treatments on patients.

Carabinieri Col. Giovanni Capasso says the investigation began over a year ago after consumer groups raised alarm about some suspicious deaths at the Polyclinic hospital in the northern city of Modena.

Capasso said nine doctors were arrested Friday on accusations of corruption, criminal association, embezzlement, defrauding the national health system and performing unauthorized experimental treatments. One was jailed while the others were given house arrest.

In addition, he said, a dozen medical equipment companies have been barred from working with the national health system for their alleged involvement in the scheme.

It wasn't immediately clear how many deaths might have been attributed to the experiments.