Carl Hester has signed a letter “universally condemning” the actions of dressage star and protegee Charlotte Dujardin.

Dujardin withdrew from the Olympics in Paris on Tuesday after a video emerged of her repeatedly hitting a student’s horse with a whip from the ground during a coaching session.

The video, which was from four years ago, was described as “an error of judgement” by Dujardin with equestrian’s governing body, the International Federation for Equestrian Sports (FEI), imposing a provisional suspension.

Dujardin famously embarked on her dressage career under the tutelage of Hester, who part-owned Valegro, the horse that propelled the rider on to the front pages when the duo secured team and individual gold in London back in 2012.

Hester, who will compete for Team GB next week, is a signatory to a letter from the board members of the International Dressage Riders Club and posted on their website.

The letter read: “The IDRC universally condemn the actions of Charlotte Dujardin as seen in the video footage which was made public this morning by Stephan Wensing from European Equine Lawyers on behalf of his client.

“The Board members are resolute that equine welfare must always be placed uppermost and at all times. They promote only ethical training methods and practices and strive to encourage all their members to abide by the ‘International Equestrian Federation (FEI) Code of Conduct for the Welfare of the Horse’ together with all FEI regulations which support and protect equine welfare standards both in and out of competition.

“The IDRC Board supports the actions taken by the FEI, the British Equestrian Federation and British Dressage to provisionally suspend Ms Dujardin.

“It notes that Ms Dujardin has stated she has no excuse for her actions and has also expressed her shame and regret. Due to the live and on-going investigations the Board will not make any further official announcements on this matter until the investigations are concluded.”

British Dressage chief executive Jason Brautigam conceded it would be “incredibly difficult” for the team to compete in Paris and also revealed they will conduct their own disciplinary process after Dujardin’s actions.

“Contrary to some reports, we did not receive any complaint or have any sight of the video prior to this week,” Brautigam said in a statement on Thursday night.

“We always protect and support whistleblowers and would encourage anyone with evidence of equine abuse to come forward at the earliest opportunity.

“We fully support the FEI in the actions they have taken in response to this incident and have reciprocated the provisional six-month suspension with immediate effect.

“The individual concerned will be subject to our own disciplinary processes, but we will not be making any further comment on the specifics until the FEI’s investigations are complete.

“In the immediate future we need to rally our support around Carl, Lottie (Fry) and Becky (Moody) as they fly the flag for Team GB in Paris over the next ten days.

“It will be incredibly difficult for them to compete in such circumstances, but we need to show that we’re right behind them all the way, as they aim to bring home medals and showcase the best of our sport.”

A day after horse welfare charity Brooke dropped Dujardin as an ambassador, the prestigious London International Horse Show followed suit.

The annual event held just before Christmas was where Dujardin and Valegro broke world grand prix and freestyle records in 2014 that still stand.

“Following the recently released historical video footage of Charlotte Dujardin and the ongoing investigation being undertaken by the FEI, the London International Horse Show has made the decision that it would not be appropriate for Charlotte Dujardin to continue in her role as an ambassador for the 2024 edition of the show,” a statement on the show’s website read.

“Horse welfare is always at the forefront of all our activities.”

Two of Dujardin’s sponsors, meanwhile, confirmed they had ended their arrangements with her.

Dave Derby, chief executive of riding helmets manufacturer Charles Owen, said on Facebook: “We will not be commenting on the specific allegations as there is an ongoing FEI investigation into the matter.

“However, as a globally-respected brand known for our work in improving rider safety and promoting horse welfare, Charles Owen considers any actual or perceived mistreatment of any horse to be totally unacceptable at any level of the sport.

“Charles Owen and Miss Dujardin have had a successful partnership for many years, but while we understand the sentiment of her public statement, we have decided to terminate our sponsorship agreement with Miss Dujardin with immediate effect.”

And Fairfax Saddles, posted on Facebook: “We are shocked and saddened by the video depicting one of the well-know users of our products, Charlotte Dujardin.

“Welfare of the house is of paramount importance at Fairfax Saddles, and we do not condone this kind of behaviour.

“As a result, we are withdrawing our association with her with immediate effect, but will manage the wind-down of our technical support in a way that does not prejudice the interests of the horses, which are our primary concern.”