CHICAGO • A gymnastics coach in the US state of Wisconsin is facing child pornography charges for secretly recording athletes in his training centre locker room and bathroom, police announced.

The accusations against James Kivisto, 49, come as USA Gymnastics, the sport's governing body, is reeling from an expansive sexual abuse scandal involving former star doctor Larry Nassar, who molested hundreds of gymnasts.

A sheriff in the Midwestern state said investigators found at least 100 "inappropriate images" on electronic devices owned by Kivisto, who lived in and operated the Wind Lake Gymnastics Centre, a facility he owned for 11 years in a suburb of the city of Milwaukee.

Kivisto was a coach at other facilities dating back to 1987, police said, adding that they expect to find more images as they continue to examine his devices.

Racine County Sheriff Christopher Schmaling noted that Kivisto had listed more than 800 students on his facility's ledger. "We know that there are going to be hundreds of victims," he said on Thursday.

"We're going to expose every aspect of this disgusting man's character dating back to 1987."

Kivisto was arrested on Tuesday after a parent reported finding a hidden camera in the gym's bathroom. Police discovered additional cameras in the locker room.

"He admitted that he viewed those images for his own personal satisfaction," the sheriff said, adding that investigators had so far not discovered any evidence of abuse or that he distributed the images online.

Kivisto is in jail in lieu of US$500,000 (S$656,300) bail.

The Wind Lake Gymnastics Centre claims on its website that it is a "USA Gymnastics member club", and has met safety and background check requirements set by the governing body.

USA Gymnastics said it has now suspended Kivisto's and the club's memberships, in response to the criminal allegations.

AGENCE FRANCE-PRESSE