Prosecutors said on Sunday that the 50-year-old doctor had admitted to giving "various substances and psycho-drugs" to 12 patients during a group therapy in his Berlin practice.

One patient managed to send a text message to emergency services as all 12 collapsed with poisoning symptoms during Saturday's group session.

A 59-year-old man died soon after the drugs were administered and a 28-year-old man in a coma died later in hospital.

Police said a third man was in critical condition, but the other nine had been discharged from hospital.

A murder investigation has been launched. Interrogators said they had no evidence yet that the doctor had deliberately wanted to kill any of his patients.

It is unclear why the doctor administered the risky mix of psycho drugs, but media reports suggest he wanted to tap his patients' subconscious during the psychotherapeutic session.

Reports in Sunday newspapers said the psychology patients were offered a cocktail of heroin, amphetamines and ecstasy, but police have not yet confirmed this.

nk/dpa/AP

Editor: Andreas Illmer