Athletics sponsor Nike has revealed that no evidence has been found to implicate trainer Alberto Salazar in alleged doping offences.
The 56-year-old American, who coaches double Olympic champion Mo Farah, strenuously denied the allegations in a 11,600-word open letter that was published on the Nike Oregon Project website on Wednesday.
Earlier this month, a BBC Panorama documentary aired the accusations, which also involve American long-distance runner Galen Rupp, who is one of the athletes trained by Salazar.
The experienced coach gave a detailed rebuttal of the allegations and stated that he "will never permit doping".
Now, Nike has released a statement, which reads: "We take the allegations very seriously as Nike does not condone the use of performance-enhancing drugs in any manner.
"Both Alberto and Galen have made their position clear and refute the allegations made against them, as shown in Alberto's open letter. Furthermore, we have conducted our own internal review and have found no evidence to support the allegations of doping."
Salazar has called for the BBC and ProPublica to immediately release retractions to their "false statements".