Britain's joint-most decorated female Olympian Charlotte Dujardin pulled out of the Paris Games and was provisionally suspended for six months after equestrian's governing body launched an investigation into her conduct.
Dujardin did not elaborate on the investigation but the International Federation for Equestrian Sports (FEI) revealed they were looking into an old video where she had engaged in "conduct contrary to the principles of horse welfare".
"A video has emerged from four years ago which shows me making an error of judgement during a coaching session," the 39-year-old said in a statement on Instagram.
"Understandably, the International Federation for Equestrian Sports (FEI) is investigating and I have made the decision to withdraw from all competition - including the Paris Olympics - while this process takes place.
"What happened was completely out of character and does not reflect how I train my horses or coach my pupils, however there is no excuse. I am deeply ashamed and should have set a better example in that moment."
The FEI said they had received the video from a lawyer but the complainant was undisclosed. The FEI did not elaborate on the incident.
"According to the information received, the footage was allegedly taken several years ago during a training session conducted by Ms Dujardin at a private stable," the FEI said.
"Ms Dujardin was given a deadline of 17:00 Swiss time on 23 July to respond to the allegations. Subsequently, Ms Dujardin confirmed that she is the individual depicted in the video and acknowledged that her conduct was inappropriate.
"Charlotte Dujardin requested to be provisionally suspended pending the outcome of the investigations and voluntarily withdrew from the Paris 2024 Olympic Games."
Dujardin also confirmed to the FEI that she will not participate in any competitions pending the outcome of the investigation. She cannot participate in any British Equestrian Federation events either.
She said she was "sincerely sorry" for her actions and was 'devastated' on letting down the team, fans and sponsors.
"I will cooperate fully with the FEI, British Equestrian Federation and British Dressage during their investigations, and will not be commenting further until the process is complete," she added.
Dujardin won three golds, a silver and two bronze medals at the London, Rio and Tokyo Games in individual and team dressage.
With six medals, she is Britain's joint-most decorated female Olympian alongside cyclist Laura Kenny.
"We are deeply disappointed with this case, especially as we approach the Olympic Games in Paris 2024. However, it is our responsibility and crucial that we address any instances of abuse, as equine welfare cannot be compromised," FEI president Ingmar De Vos said.
"Charlotte has expressed genuine remorse for her actions, and we recognise and appreciate her willingness to take responsibility.
"Despite the unfortunate timing, we believe this action reaffirms the FEI's commitment to welfare as the guardians of our equine partners and the integrity of our sport."
Dujardin, ranked fourth in the FEI world dressage standings, was set to ride 11-year-old gelding Imhotep in Paris. She won team gold in the European Championships in September last year.
Becky Moody riding Jagerbomb is the alternate for the British team. The equestrian events at the Paris Olympics begin on Saturday.
- Reuters