The RSPCA has been passed information about a viral clip showing Sir Mark Todd whipping a horse with a branch.
The video, which appeared on social media over the weekend, caused widespread outrage and it is now being investigated.
Todd, a racing trainer, apologised for his actions in the footage, which showed him striking the horse ten times.
With a rider in the saddle, the animal hesitated as it was about to cross a water obstacle.
The clip, understood to be two years old, is being probed by various bodies including the British Horseracing Authority.
A spokesperson for the RSPCA, which intervened in the recent case of footballer Kurt Zouma, said: "We are aware of this upsetting video. We have been given information which suggests this happened in another country but we would encourage anyone with first hand information to contact their nearest Society for the Prevention of Cruelty to Animals.
"Our emergency line is 0300 1234 999."
Todd, a double Olympic champion in eventing, was knighted in 2013 for services to equestrian sports.
But the scenes of him using the branch while training a rider led to him stepping down from his role with World Horse Welfare.
The gold medal winner from the 1984 Los Angeles Olympics and Seoul four years later was a patron for the charity.
The FEI, the world governing body for sports including eventing and dressage, responded to the clip on Tuesday.
"The FEI is disappointed and alarmed by the images in the video," a spokesperson said.
"This is not acceptable behaviour and it goes against everything we stand for and the values we encourage and expect from all horsemen and horsewomen.
"Every individual in the equestrian community has a responsibility and a duty to safeguard and protect the horses in their care and embrace a zero tolerance attitude when it comes to any form of equine abuse and mistreatment.
"Any violation of that important responsibility cannot be overlooked or condoned, and the FEI will investigate whenever sporting and training methods are in clear disregard of the health and welfare of our most valued partner, the horse.
"The foundations of our sport rest on our partnership with the horse, and it is up to all equestrians to uphold and respect this core principle in the pursuit of sport and leisure riding."
Todd's involvement in the video comes nearly a year after fellow racing trainer Gordon Elliott was pictured sitting on a dead horse.
The Irishman, who has dual Grand National winner Tiger Roll in his stable, received a six-month ban.
It is not yet clear whether Todd will be penalised by the BHA.
The 65-year-old, who had 13 winners on racing tracks in 2021, issued an apology in the aftermath of the video being widely shared.
"I wholeheartedly apologise to the horse and all involved for my actions in this video clip," he said.
"One of the main things I preach is about establishing a mutual respect between horse and rider and that patience and kindness is the best way to get results.
"I believe this is one of the main attributes along with a great empathy with animals that has enabled me to have a long and successful career in eventing.
"I am very disappointed in myself that I did not adhere to that in this case."
