The judges' decision comes a month after financial prosecutors formally accused Diack and his son Papa Massata of a host of illicit practices over a period of years with the active involvement of international athletes and their federations.
Money laundering alone carries a jail term of up to 10 years.
Diack, who led the IAAF from 1999-2015 and was one of the most influential men in athletics, and his son have consistently denied wrongdoing.
Prosecutors began their investigation in 2015, shortly after the IAAF's ethics commission and the World Anti-Doping Agency (WADA) uncovered evidence a Russian marathon runner paid 600,000 euros ($683,220) to cover up a positive drug test, allowing her to compete in the London 2012 Olympic Games.
The prosecutors in their indictment highlighted what they describe as the "extremely complacent" attitude of the IAAF towards the Russian athletics federation. They set out the relations between a number of IAAF and national federation officials allegedly involved in corrupt practices.
According to the prosecutors, Diack and his son, who oversees a sports consulting business called Black Tidings, solicited payments from athletes, either directly or indirectly, totalling 3.45 million euros (3.09 million pounds) in exchange for covering up positive doping tests and allowing athletes to go on competing.
(Reporting by Emmanuel Jarry; Writing by Richard Lough; Editing by Luke Baker and Christian Radnedge)
