A 46-year-old chief internist at a public hospital here was acquitted Friday of charges of poisoning seven colleagues in October 1998.

Citing a lack of proof, the Kyoto District Court acquitted Hiroshi Ishida, who had been charged with mixing a toxic chemical into water in an electric urn in an Utano Hospital staff room.

Presiding Judge Hiroshi Fukukawa also determined that police acted illegally by forcing a confession out of Ishida during his interrogation.

Seven doctors were briefly taken ill after drinking green tea made with the water laced with sodium azide.