Team GB athlete Charlotte Dujardin has withdrawn from the Olympics over a video from four years ago showing her making "an error of judgement" during a coaching session.
Dujardin, a three-time Olympic champion, has decided to pull out of all competition while the International Federation for Equestrian Sports (FEI) investigates the incident.
The video shows Dujardin repeatedly hitting a student's horse with a whip from the ground, according to the Dutch website horses.nl.
In a statement Dujardin said: "A video has emerged from four years ago which shows me making an error of judgement during a coaching session.
"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.
"I am sincerely sorry for my actions and devastated that I have let everyone down, including Team GB, 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."
Dujardin, 39, could have become Britain's most decorated female Olympian in Paris. A medal of any colour would have taken her clear of Laura Kenny, with whom she is currently tied on six medals.

Snoop Dogg among torchbearers
Snoop Dogg will be among the torchbearers carrying the Olympic flame in the final stretch before the opening ceremony of the Paris Games on Friday.
The American rapper, whose decades of hits include "What's My Name" and "Drop It Like It’s Hot", is in the French capital as a special correspondent for American network NBC.
Snoop, whose real name is Calvin Broadus Jr, posted a photo on X of himself standing outside the Hotel de Ville with the caption: "U Ready? Paris 2024 Olympics ya digggg", with gold medal and boxing glove emojis.
Last month the rapper, who was born in Los Angeles, which will host of the 2028 Games, limbered up for his Olympic stint by posting a time of 34.44 seconds over 200 metres in a special exhibition race at the US trials.
The 68th stage of the torch relay will see it travel through the Olympic Village and past both the Aquatics Centre and the Stade de France, before it is taken to the banks of the Seine for the final stage of its journey.
Snoop Dogg, 52, will carry the torch through the streets of Saint-Denis, the underprivileged northern Paris suburb that is home to the Stade de France Olympic Stadium, the town's mayor Mathieu Hanotin said on social media platform X.
"Saint Denis: last step before the Eiffel Tower. An international cast @SnoopDogg for the last stretch of the Olympic Flame," Hanotin wrote.
The rapper is better known in the sports world for his Snoop Youth Football League. The championship game is called the 'Snooper Bowl'.
Other carriers of the torch in Saint-Denis on Friday include French actress Laetitia Casta and French rapper MC Solaar.
Surf's up

While most 2024 Olympians will be battling for glory in Paris, the world's best surfers will be going for gold some 16,000km away on the island of French Polynesian island of Tahiti, where the spinning blue barrels of Teahupo'o might be the real star of the show.
Competition is likely to be fierce between the sport's traditional powerhouses but host nation France are a genuine threat after two Tahitians, Vahine Fierro and Kauli Vaast, qualified to compete at their home break.
"Hosting the Olympics at Teahupo'o is the best spot they could ever pick just because it's such a good wave at that time of the year," said local woman Vahine Fierro, who won the Tahiti Pro in pumping waves in May.
"I think the Olympics are going back to where the surf was born."
Surfing was recorded in French Polynesia, now an overseas territory of France, as early as the 12th century but only made its first Olympic appearance in Tokyo in 2021.
The surf contest in front of the idyllic lagoon-side village of Teahupo'o will bear little resemblance to Tokyo, let alone the exploits of those early wave-riders.
While Italo Ferreira and Carissa Moore carved and spun their way to gold in the murky, typhoon-churned waves of Japan's Shidashita beach, Teahupo'o breaks perfectly over a coral reef and is renowned for its heavy, hollow tubes.
"You can have the most craziest experience, your best feelings, the best wave you can have in your life, and you can also can have the worst wipeout in your life," said local man Vaast.
"To surf Teahupo'o you have to be really good at surfing. You have to not be scared because it's a wave that you have to have skills to surf it. It's not everyone that can surf this wave."

Teahupo'o, which translates as "Pile of Heads" or "Wall of Skulls" after a gruesome local legend, was picked to stage the Olympic competition because the beaches in France are mostly flat this time of year.
While the biggest waves rise some 10m and are not as tall as those in Portugal's Nazare or Hawaii's Peahi, the explosive power, giant tubes and sheer volume of water set Teahupo'o apart.
Huge storms in the South Pacific generate swells of 9-12m which travel thousands of kilometres before lurching out of deep water onto the shallow reef.
A deep trench carved by fresh water running off the jungle-clad mountains provides an incredibly close and relatively safe spot for spectator boats, while judges will watch from a controversial new tower built into the reef itself, which was reduced in size slightly after local protests.
Surf forecasting website Surfline is predicting good odds for a stronger-than-normal swell during the Olympic competition window from 27July - 8 August.
Refugees
🔊 The Refugee Olympic Team for #Paris2024 has been officially announced!
— Refugee Olympic Team (@RefugeesOlympic) May 2, 2024
Thirty-six athletes are set to represent more than 100 million refugees. ❤️
Click the link to discover who the athletes are! ⤵️
Members of the refugee Olympic team will have their voices heard around the world during the Paris Games, increasing awareness for millions of displaced people, but they are equally ambitious in the hunt for medals, the team's flag bearers said today.
The International Olympic Committee (IOC) has assembled its largest refugee team to date for the 2024 Games starting on Friday, with 37 athletes.
The athletes, from countries including Syria, Sudan, Cameroon, Ethiopia, Iran and Afghanistan, will compete across 12 sports in Paris, the third time such a team has been formed for the Summer Olympics.
"Just for our name 'refugee Olympic team' to be called out, refugees all around the world will acknowledge us," Cameroon-born boxer Cindy Ngamba, currently based in Britain, said.
"We are seen as a team, we are seen as athletes, as fighters, hungry athletes who are part of a family.
"We are not afraid, not ashamed and are proud to be refugees. We know we are not with them but we can feel the energy."
The IOC unveiled its first refugee team for the Rio 2016 Games with 10 athletes to raise awareness of the issue as hundreds of thousands of people were pouring into Europe from the Middle East and elsewhere escaping conflict and poverty.
The team that competed at the Tokyo 2020 Olympics, held in 2021 due to the COVID-19 pandemic, was already almost three times bigger than the Rio team, with 29 athletes.
But the team in Paris is the largest while also having its own emblem.
"It matters 100%," Ngamba said of the emblem. "The foundation is about the team, about a family. Being part of the unique family is what it is all about.
"We competed individually in the past, or 2-3 of us. Now we are a big group, a family going out there to represent the refugee team. We will hold our head high and be proud of the team we are part of.
"It shows we are not just refugees, we are athletes. (People) see us as refugees but forget we are athletes with the same goals as the other countries represented here. We can achieve the same thing, win the same thing, have the same drive, the same hunger and the same energy."
For co-flagbearer Yahya Al Ghotany, who was forced to leave war-torn Syria and will compete in taekwondo, the team was sending a message of hope. Al Ghotany only picked up the sport once he was at a refugee camp in Jordan.
"It is a wonderful feeling knowing I am representing many people who have gone through the same experience as me, just like me," he told Reuters. "Representing more than 100 million displaced people across the globe."
"It is very important because it sends a message of hope. There is always hope in passion," he added.
Watch the 2024 Olympic Games with 14 hours of televised action on RTÉ2 and RTÉ Player each day. Listen to extensive radio coverage on RTÉ Radio 1 and 2fm's Game On and follow each moment from Paris on RTÉ.ie, the RTÉ News app and all RTÉ digital platforms. Listen to the daily RTÉ Sport Olympics Podcast.