Alberto Salazar, the coach of Britain's Olympic champion Mo Farah, has denied administering banned supplements to his athletes and issued a firm rebuttal of what he said were false allegations against him in a British newspaper.
The Sunday Times earlier reported that Salazar had used prohibited infusions of supplements to improve the performance of his runners, citing what the newspaper said was a leaked United States Anti-Doping Agency (USADA) report.
But the coach, who was accused of violating anti-doping rules in a BBC documentary in 2015, said on Sunday that the newspaper had "recycled old allegations" he had already refuted.
The Sunday Times was not immediately available to comment.
"I have clearly and repeatedly refuted allegations directed against me and the Oregon Project," Salazar said in a statement referring to Nike's training centre for elite distance runners.
"I believe in a clean sport and a methodical, dedicated, approach to training. The Oregon Project will never permit doping and all Oregon Project athletes are required to comply with the WADA (World Anti-Doping Agency) Code and IAAF (International Association of Athletics federations) Rules.
"I do not use supplements that are banned."
The Sunday Times said Farah and other athletes coached by Salazar were given infusions of a research supplement based on the chemical L-Carnitine and that one athlete who was given a high dosage said it was as effective as illegal blood doping.
Responding to the newspaper report, Farah said in a statement that he was "a clean athlete who has never broken the rules in regards to substances, methods or dosages".
Salazar, a Cuban-born American marathon runner who has worked with Farah since 2011, said his athletes had used L-Carnitine but added in his statement that it was not a banned substance and had only been administered after he had checked in writing with USADA about what its guidelines were.
"L-Carnitine is a legal nutritional supplement that is not banned by WADA," he said. "Any use of L-Carnitine was done so within WADA guidelines.
"I also communicated in writing with USADA in advance of the use and administration of L-Carnitine with Oregon Project athletes... who were then administered L-Carnitine in exactly the same way USADA directed."
Salazar added: "The leaking of information and the litigation of false allegations in the press, is disturbing, desperate and a denial of due process.
"I look forward to this unfair and protracted process reaching the conclusion I know to be true."
Nike also issued a statement on Sunday, saying: "Alberto has clearly and repeatedly refuted the allegations directed against him and the management of Oregon Project. Nike strongly believes in clean sport."
Salazar did not address in his statement further allegations in the British newspaper that the leaked USADA report also accused the coach of abusing prescription medicines for his athletes, including Farah, in the belief performances would be boosted through increased testosterone levels.
The Sunday Times, citing the USADA report, said Farah's British doctors had intervened because they were concerned about the effects on his health.
Farah, who last year became only the second man to retain the Olympic 5,000 and 10,000 metres titles, said the newspaper had used his profile to make "the story more interesting".
"If USADA or any other anti-doping body has evidence of wrongdoing they should publish it and take action rather than allow the media to be judge and jury," he added.
After the 2015 BBC documentary, Farah was exonerated by UK Athletics who found no impropriety on his part from the initial findings of a review into his relationship with Salazar.
The Sunday Times said the USADA report had been leaked by the 'Fancy Bears' hacking group.
USADA on Saturday confirmed to Reuters that the document cited by the Sunday Times appeared to have been leaked but would not comment on the report's conclusions or any accusations against Salazar.
"USADA can confirm that it has prepared a report... regarding care given by a physician to athletes associated with the Nike Oregon Project," USADA Communications Manager Ryan Madden said in an email to Reuters.
"It appears that a draft of this report was leaked to the Sunday Times by the Russian state-affiliated hacker group known as Fancy Bears.
"We understand that the licensing body is still deciding its case and as we continue to investigate whether anti-doping rules were broken, no further comment will be made at this time."
(Reporting by Simon Evans in Miami; Additional reporting by Gene Cherry, Toby Davis and Neil Robinson; Editing by Andrew Both/Keith Weir/Ken Ferris)