Olympic athlete Somluck Kamsing reported to police in Khon Kaen on Thursday and faces four charges, including attempted rape, in connection with a 17-year-old girl.
Mr Somluck was charged with taking a minor, aged above 15 but less than 18, from parents or guardians, taking a minor for indecency, committing an indecent act against a minor and attempted rape.
The 50-year-old former boxer denied the charges.
Police will talk to a motorcycle driver who allegedly took the girl and Mr Somluck from an entertainment venue to a hotel to be charged with conspiracy.
The teenage girl, whose name was withheld, accused Mr Somluck of sexual assault. She said that after meeting at a pub, Mr Somluck took her to a hotel where she was sexually assaulted. The incident occurred at about 3.30am on Dec 10.
Mr Somluck, a former Muay Thai fighter turned boxer, earned a bronze medal at the 1989 King's Cup and a gold medal at the 1995 event. At the 1996 Summer Olympics in Atlanta, Georgia, in the United States, he made history as the first Thai athlete to win a gold medal.