This has to be the worst week for one of the country's premier sports

(Above) Sonoda bows in apology at a news conference in Tokyo.

Japan's national women's judo head coach said Thursday he would resign, a day after allegations emerged he had beaten his athletes with wooden swords. He added that in the wake of the allegations it would be "difficult" for him to stay as coach, a position that sees him training Olympic athletes.

"I would like to deeply apologise for causing trouble to all the people concerned with what I have done and said," Sonoda told a news conference.

"I think it will be difficult for me to continue being engaged in the training programme any longer. I wish to submit my resignation."

At Thursday's news conference, a contrite Sonoda made a deep bow of apology and admitted the allegations were "more or less true".