The All Japan Judo Federation issued an apology Wednesday, admitting to allegations that 15 of its top female athletes were subjected to harassment and physical violence by head coach Ryuji Sonoda and other coaching staff.

"This is something that never should have happened," said judo federation senior director Koshi Onozawa at a press conference held at the Kodokan in Tokyo's Bunkyo Ward. "We will double efforts to make sure this never happens again."

Sonoda, 39, and other coaching staff received an official warning in a letter in mid-January after being questioned by the judo federation. The judo federation said it does not intend to release the names of the women or other coaches involved and at this juncture has no plan to replace Sonoda.