(Reuters) - Organisers of the Saudi Cup, the world’s richest horse race, have said they will withhold the $20 million prize purse pending the completion of an internal investigation after winning trainer Jason Servis was indicted in a doping scheme.

Servis, who trained race winner Maximum Security, was one of 27 trainers, veterinarians, drug distributors and others charged in the United States last month in a wide-ranging scheme to drug horses and cheat bettors.

Maximum Security won Saudi Cup in February and the colt’s owner Gary West fired Servis following his indictment, replacing him with Hall of Fame trainer Bob Baffert.

The Jockey Club of Saudi Arabia (JCSA) said in a statement that its investigation into Servis had been slowed by the COVID-19 pandemic.

“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 statement said.

“The JCSA is conducting its own investigation into the allegations and until that is concluded, will withhold payment of prize money to all connections of horses placed in prize-winning positions.

“The decision has been communicated privately to connections of Saudi Cup runners. Due to difficult operational circumstances caused by the COVID-19 pandemic, the investigation is not yet concluded.”

Maximum Security held off Midnight Bisou to win the Saudi Cup with Benbatl finishing third. The winner was to receive $10 million, with the runner-up and third-placed finisher earning $3.5 million and $2 million.

Servis, who prosecutors say covertly administered performance-enhancing drugs to Maximum Security and “virtually all of the racehorses under his control,” would plead not guilty to the charges, his lawyer has said.

Maximum Security also finished first in the 2019 Kentucky Derby but was later disqualified for interference.