Saudi organisers of a race day billed as the world’s richest have been left embarrassed after the trainer of the winning horse was indicted for doping, forcing them to withhold the entire $20m prize purse.

The Saudi Cup, held on a purpose-built track in Riyadh from February 28-29, was supposed to showcase Saudi Arabia as a new global force in horse racing and add another showpiece to its fast-growing lineup of global sports.

However, an announcement by the course’s newly formed jockey club that all place-getters would forgo their earnings pending an investigation has cast a pall over the event and has raised fresh concerns about the kingdom’s new-found enthusiasm for sport and the recognition Saudi leaders believe it confers.

On Monday, race day organisers announced the suspension of winnings one month after trainer Jason Servis was charged with administering banned substances to his charges, including Maximum Security, the winning horse in at the inaugural race.

US authorities laid the charges against Sevis just over a week after the Saudi Cup. The indictment alleged that Maximum Securitywas given a performance-enhancing drug before a meet last year. The winner’s share of the $20m kitty was supposed to be $10m – a payday thought to be unrivalled in global racing.

The indictment follows a FBI probe into horse-doping across the US and alleges that Maximum Security was given SGF-1000, a designer performance-enhancing drug containing “growth factors”. At the time, the horse was the champion three-year-old colt in the country.

Servis pleaded not guilty to the charge in a New York court in March.

But in response, the Jockey Club of Saudi Arabia (JCSA) said it had told all winners that the prize pool was being withheld while it conducted its own investigation. It has hired French officials to conduct drug testing on samples taken from horses that competed in the Saudi Cup event, and says the findings will be released in due course.

“JCSA will withhold payment of prize money due to all connections of horses placed in prize-winning positions in the Saudi Cup, race 8,” a statement released on Monday by the Jockey Club said. “The JCSA is aware that Jason Servis has been indicted in the US on charges relating to the administration of prohibited substances to horses under his care and control.”

The February race day was billed in Riyadh as another event in a roll-call of sports that have been lured to the Kingdom by senior officials as part of a reform program that aims in part to make Saudi Arabia more outward-looking.

Critics contend that sport is being used as a form of soft power, primarily to generate revenues, which could subsidise the vast but dwindling and increasingly unreliable sums the country generates from oil. Last December’s world title heavyweight fight between Anthony Joshua and Andy Ruiz was held up as a success by officials – a benchmark the racing officials were keen to match.

So far this year, the kingdom has held the Dakar Rally, a stage of the PGA European Golf Tour, and the women’s European golf championship.

Before the coronavirus crisis, the Snooker Masters was scheduled for October, and officials were in talks to hold a Formula One grand prix.

The threat of the virus has also slowed the local investigation into the Saudi Cup event. Air traffic between France and Saudi Arabia has stopped and both countries are enduring lockdowns that have seriously affected workplaces.