Documentary makers have defended the Panorama programme which has caused a storm after Alberto Salazar denied allegations made in the show that he helped athletes use banned substances.
Three weeks on since the ProPublica and BBC piece, Salazar - who coaches double Olympic and world champion Mo Farah [who has not been accused of any wrongdoing]- published an 11,000-word statement online on Wednesday, insisting he believes in a "clean sport and hard work" and that he will "never permit doping".
On the eve of the US National Track and Field Championships that begin on Thursday, Salazar added: "I have spent hours reviewing information from the past 15 years. I am saddened that these false allegations have been allowed to run with little care for the carnage in their wake."
According to the Associated Press, the United States Anti-Doping Agency is investigating whether Salazar encouraged Farah's training partner Galen Rupp and others to break anti-doping rules.
More than a dozen witnesses with links to the Salazar-led Nike Oregon Project have reportedly been interviewed by USADA, who are said to be actively pursuing documents and other evidence from Salazar. The American coached Rupp to a silver medal behind Farah in the 10,000 metres at the London 2012 Olympics.
A BBC spokesperson said: "We are confident in our programme and that it was right to air the allegations of the witnesses who appeared on it. We stand by our journalism and it is now for the relevant anti-doping authorities to investigate the allegations.
"The detailed allegations were put to Mr Salazar four weeks before the programme aired giving him the opportunity to address them in full.
"The BBC has also invited Alberto Salazar to be interviewed about the allegations, an offer which still stands. Almost two months after Mr Salazar was first made aware of the allegations, we welcome his more detailed response."
ProPublica have also issued a statement in response to Salazar's open letter.
"Mr. Salazar's statement confirms some details of our story, and purports to contradict other things that were not actually in the story," said ProPublica editor-in-chief, Stephen Engelberg.
"We will soon be detailing this, but can say now that we see nothing in the statement that would merit a correction. We also note that we informed Mr. Salazar of the details of our reporting seven weeks ago, four weeks before it was published."
Last week, Farah denied ever using performance-enhancing drugs and said he would await Salazar's response before deciding whether to stick with his coach.
Farah, who has not been accused of anything illegal, has come under scrutiny after a report in the Daily Mail claimed he missed two drugs tests in the build-up to London 2012, where he won 5,000 and 10,000m gold.