Japan coach Alberto Zaccheroni has spoken of his shock upon learning that 15 top female judo wrestlers, some of them London Olympians, were slapped, beaten with wooden swords and told to "die" by their head coach Ryuji Sonoda.

News of the scandal broke Tuesday and Sonoda, 39, has acknowledged the claims of physical and verbal abuse the women submitted to the Japanese Olympic Committee at the end of last year. He announced his resignation at a press conference on Thursday, shortly after Italian tactician Zaccheroni announced his squad for a World Cup qualifying warmup against Latvia in Kobe next week.

"Firstly it is difficult to imagine anything like this happening in Italy," Zaccheroni told reporters. "I was very surprised upon learning this news. It is real shame that this kind of incident has happened."

The tacit use of corporal punishment in Japanese sports has a long history but has come to the fore in recent years after a spate of scandals including the hazing death of a teenage junior sumo wrestler in 2007 and, most recently, the suicide of a high school student in Osaka after he was repeatedly beaten by the school's basketball coach.

"An instructor's most important role is to raise the athletes, but violence is not necessary to achieve that goal," said Zaccheroni. "Of course as coaches we get angry and express our emotions but that should not lead to physical punishment."

He added, "I can't speak too much about this as I only have a small amount of information, but I would like to think this is a rare case and pray it never happens again."