The Italian, who was being probed for "conspiracy to cause injuries to professional athletes through doping", was released without charge on the first day of his scheduled hearing.

"The case is withdrawn," Nairobi magistrate Bernard Ochoi confirmed.

Rosa's lawyer James Nyiha told Reuters: "My client should not have been charged in the first place.

"The state did not have an iota of evidence against my client."

Rosa's case was withdrawn under Section 87A of the criminal procedure code, which also stipulates that a suspect can be rearrested in future and charged with the same offence if more evidence emerges.

Rosa had denied six counts of doping athletes.

He and his father Gabriele were both subject to questioning by Kenyan police in connection with the investigation.

Hotel rooms belonging to the two leading agents, whose company represented banned Kenyan athletes such as Rita Jeptoo, were searched by police during the country’s Olympic trials in Eldoret.

Jeptoo was suspended in 2014 for two years following a positive test for erythropoietin (EPO).

The company run by the Rosa pair also represents the likes of half marathon specialist Matthew Kisorio, who served a doping ban until last year, and Agatha Jeruto, who was banned for four years in October after she tested positive for norandrosterone.

Kenya claimed a record haul of six gold, six silver and a bronze at Rio 2016, all in athletics, but faced a controversial build-up in which the International Olympic Committee (IOC) imposed special eligibility criteria.