"I talked to her because she was cute. But I was worried that my football career would be finished if I got caught," police quoted him as saying after he admitted the allegations.

Police said the 22-year-old had sexual relations with the high school girl, who is legally a minor, in the central Japanese city of Hamamatsu last month.

Kikuchi was caught because he left his wallet containing his driver's license in the basket of the girl's bicycle, police said.

"I sincerely apologise to the girl who fell victim in this incident," Iwata president Hiroshi Ukon told reporters on Wednesday at a hastily-arranged press conference at the team's home stadium.

"I feel heavy responsibility as the president, as the club did not guide him enough. We are here to coach professional athletes to be models for young people.

"We are going to punish him severely. At the same time, we are going to examine ourselves so as not to repeat the same incident," he said.

J-League chairman Kenji Onitake separately said he was disappointed by Kikuchi.

"On behalf of the league, I must apologise to the fans and concerned people," he said.

Kikuchi, 22, joined Iwata in 2003 and also played for Albirex Niigata in 2005 before becoming part of Iwata's starting team last season. He has scored five goals in 93 games in the league competition over six years.