Salazar, who also coaches Britain’s Olympic and world 5000m and 10,000m champion Mo Farah – about whom no allegations have been made – said in the letter that he "will never permit doping" among his athletes.

The BBC Panorama investigation in collaboration with United States  journalism organisation ProPublica claimed that Rupp, 29, was given the banned anabolic steroid testosterone in 2002, when he was 16-years-old.

In his letter, Salazar denies that Rupp has ever taken a banned substance, and Rupp has also denied the claims.

No allegations were made against other NOP athletes in the investigation, including Britain's world and Olympic 5,000 and 10,000m champion.

Cuban-born American Salazar added in the statement, published on the NOP website, that his athletes had to "fully comply" with the World Anti-Doping Agency (WADA) code and International Association of Athletics Federations (IAAF) rules.

He continued: "I am saddened that these false allegations have been allowed to run with little care for the carnage in their wake.

"I am always extra cautious and take every step to ensure my athletes comply with the anti-doping rules."

Defending Rupp, who won Olympic 10,000m silver behind Farah at London 2012, Salazar writes: "Galen suffers from severe allergies and breathing issues.

"He is medically diagnosed as suffering from both asthma and Hashimotos disease, a thyroid disease.

"Galen is one of the hardest working, most honest and genuine athletes I have ever known. Galen has never taken a banned substance in violation of the WADA code."

Salazar, who claims the allegations were based on "nothing but innuendo, hearsay and rumour", goes on to highlight Rupp's medical history in detail as well as details of thyroid and asthma medicine use in the NOP.

He also provides figures to answer claims about the alleged abuse of therapeutic use exemptions, or  therapeutic use exemption (TUEs), which permit athletes to use certain substances to treat some conditions.

"We currently have nine athletes in the Oregon Project," write Salazar.

"Since 2011, those athletes have had a grand total of four TUEs.

"From these numbers it is clear that the Oregon Project is not manipulating the TUE process in any way."

The lengthy document also addresses specific claims made by individuals in the investigation.

The allegations that Rupp took testosterone as a 16-year-old in high school came from Steve Magness, who was Salazar’s number two at the Nike Oregon Project in 2011.

Salazar says Magness did not leave the Project of his own accord in 2012.

“His actions also speak volumes,” the letter said

“After reading Galen’s chart, he did not leave the Oregon Project.

“Rather he stayed for another 18 months.

“Magness didn’t leave until I terminated his contract in June 2012.

“I could only speculate about why Magness would inappropriately photograph and retain the medical records of an athlete without authorization and then wait 3 years to share it with the press.”

The letter continued: “In 2006, Justin Gatlin tested positive for exogenous testosterone.

“Gatlin asserted that he had not knowingly taken testosterone and claimed that he had been sabotaged by his massage therapist, Chris Whetstine.

“The Gatlin story was extremely well known throughout the track world.

“Rumours about whether athletes could test positive by having something rubbed on them after a race and before going to doping control were rampant.

“On May 9, 2009, Galen Rupp’s University of Oregon 4x1 mile relay team set a new NCAA record.

“Shortly after the race while talking to the press, Galen felt someone rubbing his shoulders.

“He turned around and it was Chris Whetstine.

“Galen had heard the stories.

“He was extremely concerned and called me.

“I called the USADA (United States Anti-Doping Agency) hotline to report it.

“USADA may still have the tapes or notes of my call.

“Nothing came of it but it caused us grave concern.

“The Gatlin case involved testosterone so we decided to see if rubbing Androgel on an athlete after a race could cause a positive test.

“The subjects for the experiment were my sons, who are the same approximate age as typical elite athletes and are in good physical condition.

“But are not elite athletes subject to USADA or any other elite testing pool.”

Salazar also addressed the claim made by massage therapist John Stiner that he had told him to post back a testosterone cream left at a training camp in a room being used by himself and Rupp.

Stiner alleged Salazar had said the cream was prescribed for him, as he had a serious heart condition, but that he had subsequently learned that such a treatment was counter-productive for such a condition.

“First, I have a valid prescription for Androgel,” writes Salazar

“While this is something I would not like to air publicly, I am forced to do so to protect my athletes.

“As I stated above, my excessive training as an athlete did extensive damage to my body.

“One of the lingering negative effects from which I still suffer today is hypogonadism with significant symptoms, including multiple low testosterone serum levels…

“Second, I did not tell John Stiner that my Androgel was for my heart.

"It isn’t.

"It is for my overall health.”

Following Salazar's open letter, Nike said in a statement: "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 is an "unpaid consultant" for UK Athletics, which has promised a review of his role.

It said: "The content of the statement will be referred to our Performance Oversight Group for consideration in their ongoing internal review."

A BBC spokesperson said: "We are confident in our programme and that it was right to air the allegations of the witnesseswho 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.”

To read the letter in full click here and here. 

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