It has not yet decided whether to replace horse riding with another discipline – such as cycling or climbing – or turn the sport into a four-event tetrathlon after the Paris 2024 Olympics.
The UIPM refused to confirm Telegraph Sport's information, instead suggesting an announcement will be made on Friday. A statement read: "As part of UIPM's commitment to maintaining a strong, dynamic profile for modern pentathlon, a series of strategic meetings are being held. These meetings will include an upcoming call with national federations later this week."
Choong, who won gold in Tokyo a day after Team GB compatriot Kate French claimed the women's title, said it was "very disappointing" that athletes and coaches had been left in the dark over such a major change.
"Assuming it's true, it's very sad for the sport. It's been around since the beginning of the Olympic movement in 1912," he told Telegraph Sport.
"Without horse riding, or if we changed it for another sport, it's not modern pentathlon. No other sport tests such diverse sporting prowess.
"I've just won an Olympic gold medal in the way pentathlon has been for 109 years. It's a great sport as it is. I don't want to grow up and tell my future kids that I'm the Olympic champion of a sport that doesn't exist."
Modern pentathlon, which was created by Baron Pierre de Coubertin, the founder of the Olympics, has undergone multiple changes while battling to maintain its place at the Games amid questions over its continued relevance and low viewer numbers.
One source to have followed the sport's travails branded the punching incident in Tokyo as "the straw that broke the horse's back", with images of a tearful Schleu – who had been leading at the time of her show jumping debacle – spreading worldwide.
Athletes are currently assigned a horse using a random pre-competition draw, with just 20 minutes to bond with the animal before entering the arena.
A series of rule changes have reduced the importance of horse riding in recent years, leading to a reduction in standard, although Choong says there are rule amendments that could be made to "improve the riding quality" and "prevent episodes like what happened in Tokyo with the German rider".
Having historically taken place over several days, modern pentathlon became a one-day event for Atlanta 1996, before the running and shooting disciplines were combined at London 2012, and all five disciplines held in a single stadium at Tokyo 2020. It will change again for Paris 2024, when the entire event is streamlined further to ensure it takes place within 90 minutes.
Horse riding's removal will not come into effect until the Los Angeles 2028 Games, although another source questioned whether the sport would even remain on the programme with the changes.
"If horse riding is not part of it then the sport is no longer Pierre de Coubertin's vision, so what is its worth in the Olympics?" they told Telegraph Sport. "That is what keeps it in the Games."
