By Karolos Grohmann

RIO DE JANEIRO (Reuters) - Whistleblower Yulia Stepanova, who helped expose state-backed doping in Russian sports and has fled the country, asked again on Saturday for the International Olympic Committee (IOC) to reassess her exclusion from the Rio Games.

Stepanova's hopes of running at the Olympics, which start next week, as an independent athlete where dashed when the IOC ruled earlier this month that no Russian with a doping background could take part.

In a letter to the IOC, Stepanova and her husband Vitaly, however said the middle-distance runner had earned the right to compete after having been cleared by the world athletics federation, the IAAF, and praised for her actions.

"We would herewith once more like to ask the IOC (Executive Board) to re-assess the decision on Yulia. As we have been able to show... there have been mistakes and omissions by the (IOC) Ethics Commission.

"We trust that we could also clarify that the IOC ruling on previously banned Russian athletes does not apply to Yulia as she was declared eligible to run."

But the IOC later on Saturday rejected any review of her case and had not discussed the matter at its Executive Board.

"The final decision by the IOC Executive Board has been taken already," said IOC spokesman Mark Adams when asked whether Stepanova's renewed appeal would be reviewed.

Stepanova has rejected an invitation to attend the Olympics as a guest, with the IOC arguing her drugs-tainted past made her ineligible to compete in Rio.

The athlete, who provided evidence of doping in a series of documentaries by German broadcaster ARD, has fled Russia and is living in hiding at an undisclosed location in the United States, fearing for her safety.

As a result of her revelations, Russian track and field athletes have been banned from the Games with many Russians from other sports also excluded over past doping offences.

The IOC has said any Russian athlete with a doping past, including Stepanova, would not be allowed to compete in Rio as it tightened controls following the fallout from the doping scandal involving their country.

(Reporting by Karolos Grohmann; Editing by Ken Ferris)