LONDON • Britain's four-time Olympic champion Mo Farah's coach has been accused of using prohibited drug infusions to improve the performance of his runners, The Sunday Times reported, citing a leaked United States Anti-Doping Agency (Usada) report.
The British newspaper said the 2016 report also accused coach Alberto Salazar of abusing prescription medicines for his athletes at the Nike training centre in Oregon.
Attempts by Reuters to reach him for comment were unsuccessful.
Salazar had issued a lengthy and detailed denial of similar allegations in 2015.
The Sunday Times said the report had been leaked by the "Fancy Bears" hacking group which has previously leaked medical and doping-related documents.
Usada on Saturday confirmed that the document cited by the newspaper appeared to have been leaked but would not comment on the report's conclusions or any accusations against the 58-year-old Salazar.
"Usada can confirm that it has prepared a report in response to a subpoena from a state medical licensing body regarding care given by a physician to athletes associated with the Nike Oregon Project," Usada communications manager Ryan Madden wrote in an e-mail 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."
The Sunday Times said that Farah and other athletes coached by Salazar were given infusions of a research supplement based on the chemical L-carnitine and that one coach who was given a high dosage said that it was as effective as illegal blood doping, according to the report.
It said that Salazar also e-mailed disgraced American cyclist Lance Armstrong, touting the benefits of L-carnitine.
Salazar, a Cuban-born American marathoner who has worked with Farah since 2011, was accused of violating anti-doping rules in a BBC documentary in 2015, including allegations that he had given 2012 Olympic 10,000m silver medallist Galen Rupp the banned anabolic steroid testosterone.
Farah, 33, was exonerated by UK Athletics, who found no impropriety on his part after receiving the initial findings of a review into his relationship with Salazar.
The Sunday Times article says that, according to the leaked document, Salazar took "egregious risks" and abused prescription rules by persuading Farah to take potentially dangerous doses of permitted vitamin D prescription drugs, believing it would boost his performance through increased testosterone levels.
Farah's British doctors intervened because they were concerned about the effects on his health, the paper said, citing the leaked Usada report.
At last year's Rio Games, Farah became only the second man to retain the 5,000m and 10,000m Olympic titles.