By Mitch Phillips

RIO DE JANEIRO (Reuters) - Russian whistleblower Yulia Stepanova will not appeal against her ban from the Rio Olympics, saying on Friday she was "hugely sad and heartbroken" that the IOC had not supported her and used its discretion to allow her to run as an independent athlete.

Stepanova, who helped expose state-backed doping in Russian sport and has fled the country, had been ruled out when the International Olympic Committee (IOC) banned from Rio any Russian who had served a doping suspension. She served a two-year ban for blood passport abnormalities in 2013.

The Court of Arbitration for Sport (CAS) outlawed that ruling on Thursday, potentially reopening a way in for her to compete. Several other Russians have appealed, but Stepanova, in a stinging attack on the IOC, said on Friday she would not.

"We are disappointed that the IOC turned a blind eye to the risks Yuliya had to take, and the damage to her athletic career, to expose the systematic cheating in Russia and live up to the ideals expressed in the World Anti-Doping Code," Stepanova and her husband Vitaly, a former Russian anti-doping official, said in a statement.

"For her to be called 'not ethical enough for the Games' in the media release of the IOC on July 24 is a tremendous blow."

The Stepanovas said they believed the IOC's focus on Yulia's past doping sanction shifted the spotlight away from the real issue, which is that the IOC took no action against Russia for punishing her for being a credible whistleblower by refusing to put her on Russia's Olympic team.

"At no point did the IOC, unlike the IAAF, demand publicly from the Russian sports authorities that they recognise our whistle-blowing as an important and valuable contribution for clean sport in Russia," they added.

"Our disappointment and sadness is huge. We asked the IOC humbly that Yuliya, as she would never be nominated by the Russian Olympic Committee, be permitted to compete as a neutral athlete at the Games in Rio.

"While Russia was permitted to send hundreds of competitors to the Games, Yuliya's request was denied. Although we are heartbroken, we wish to clarify that we have from the beginning chosen to not follow a judicial path."

The Stepanovas said they understood that the IOC had discretion to invite anyone it chose to the Games and, having been cleared by the International Association of Athletics Federations, had been hoping to be in Rio.

"We believe that in exercising this discretion to deny Yuliya a place in the competition, it sends a message that the World Anti-Doping Code and the values of Olympism are merely words on a page," they said.

"As a result, we will not file an appeal to CAS."

(Additional reporting by Gene Cherry; Editing by Ed Osmond and Andrew Hay)