The Jockey Club of Saudi Arabia (JCSA) is withholding prize money for the $20 million (Dh73m) Saudi Cup after trainer Jason Servis was indicted in America last month.
The handler was was one of 27 individuals indicted by the District Attorney for the Southern District of New York in Manhattan as part of an investigation into alleged doping.
Servis sent out Maximum Security to win the contest in Riyadh in February, but prize money for the race will not be paid until the JCSA has carried out its inquiries.
A statement said: "JCSA is conducting its own investigation in respect of the allegations and until that investigation is concluded, JCSA will withhold payment of prize money due to all connections of horses placed in prize-winning positions in the Saudi Cup. This decision has been communicated privately to connections of Saudi Cup runners.
"Due to difficult operational circumstances caused by the Covid-19 global pandemic, the investigation has not yet concluded. JCSA will issue no further statement until such time as the investigation is completed to our satisfaction."
Maximum Security, who is jointly owned by Gary and Mary West and the Coolmore triumvirate of John Magnier, Michael Tabor and Derrick Smith, is now in the care of Bob Baffert.