A 17-year-old girl has filed a complaint with Muang Khon Kaen police in the northeastern province of Khon Kaen, accusing Olympics boxing gold medalist Somluck Kamsing of sexual assault.
Police were expected to issue a summons for the former Olympic boxing hero to acknowledge the charge.
Mr Somluck, aged 50, on Monday insisted on his innocence, expressing his exasperation, and said once the case was settled he would move to live in France.
The girl, whose name was withheld, is from Nong Kung Si district of Kalasin province. She told police when she filed her complaint on Sunday that she met Mr Somluck at a pub in Muang district, Khon Kaen province, on Saturday night.
The former boxer took her to a hotel room about 3.30am on Sunday. There, she was sexually assaulted by Mr Somluck, she alleged.
Contacted by reporters, Mr Somluck said he had been informed of the complaint and had hired a lawyer to fight the charge.
Interviewed on TV Channel 8, he said while in the pub he was befriended by the girl, who asked for a selfie photograph with him. Following some intimacy, he took her to the hotel. Mr Somluck said they had both taken off their clothes. Before going further, he had asked how old she was. When the girl replied she was 17, he stopped making advances and fell asleep.
Mr Somluck said he did not go any further than that, and was certain of his innocence.
Channel 3 news anchor Sorayuth Suthassanachinda posted on his Facebook that Mr Somluck had confirmed in an interview with him that he did not make further sexual advances on the girl after learning she was only 17.
Pol Col Yossawaj Kaewsuebthannij, the Muang Khon Kaen police chief, said there were two aspects to the case. The first part was about the alleged sexual assault, and the second about the pub allowing entry to people under the age of 20.
The 17-year-old who filed the case against Mr Somluck had been in the care of the Khon Kaen home for minors. She would be interviewed by police investigators in company with social welfare officials. More witnesses at the pub and the hotel would also be questioned.
The pub manager had been summoned, questioned and charged with allowing entry to people under 20, and with staying open beyond legal hours, Pol Col Yossawaj said.
Mr Somluck told the Bangkok Post on Monday that he would remain in Khon Kaen, his home province, until the case is over, and then move overseas.
"After the case is over, I will go and live in France. I am tired of this kind of social affair. I insist I did not rape or hurt her. I have not yet received a police summons, but I am ready for it and will fully cooperate with the police," he said.
Mr Somluck was a Muay Thai fighter before turning to boxing. He earned a bronze medal at the 1989 King's Cup and a gold medal in the 1995 edition. At the 1996 Summer Olympics in Atlanta, Georgia, in the United States, he won a gold medal in the men's featherweight division. He was the first Thai athlete to win a gold medal at the Olympics.