Geneva (Agencies): In a bizarre incident, a 54-year-old man has admitted to have sexually abused more than 100 handicapped children in care homes in Switzerland and Germany over a period of 29 years.

The abuse happened in nine different care homes where the unidentified man had worked as a therapist since 1982, police in the canton (state) of Bern said.

The man was held in April 2010 and has been detained since, but authorities only released details of the case on Tuesday to prevent the probe from being impeded by media interest, police said.

The head of Bern police's special investigations unit, Gabriele Berger, said in Bern that the evidence against the man includes photos and hours of video recording the abuse.

The man admitted sexually abusing 114 mentally handicapped children, some of whom also were physically impaired, police added. He also admitted eight further cases of attempted abuse, authorities said.

"One of the central questions of this investigation is how such levels of abuse could go undetected for so long," Berger pointed.

The man had been investigated on allegations of sex abuse in 2003, but that probe was dropped due to contradictory evidence, she said, adding that that case would be reopened.