Charlotte Dujardin, Britain’s joint-most decorated female Olympian, has pulled out of Paris 2024 after a video emerged showing her “making an error of judgement”.
The six-time dressage medallist said she is under investigation from the International Federation for Equestrian Sports (FEI) and will “withdraw from all competition while this process takes place”.
The 39-year-old also said she was under investigation from the British Equestrian Federation and British Dressage.
“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,” she said in statement.
“I am deeply ashamed and should have set a better example in that moment.”
Dujardin added her actions were “filmed four years ago” and that she is “devastated to have let everyone down”.
BBC Sport has not seen the video in question and it is currently unclear what the nature of the investigation is.
Dujardin won team and individual gold medals at the London 2012 Games on horse Valegro and the pair went on to win individual gold and team silver four years later in Rio.
On a different horse, Gio, she won two bronzes at the delayed Tokyo 2020 Games.
Dujardin had been set to compete in both the individual dressage and team event alongside Carl Hester and world champion Lottie Fry, on new horse Imhotep.
She needed a medal of any colour to take the outright lead as most-decorated British female Olympian from now-retired cyclist Dame Laura Kenny.
Becky Moody is Team GB’s alternate for the team event with her horse Jagerbomb.