Speaking emotionally at a hearing at the US Senate, Biles said that the “burden” of Nassar’s abuse continue to affect the gymnasts abused while in the disgraced doctor’s care.
Biles withdrew from several events at Tokyo 2020 to focus on her mental health.
“The scars of this horrific abuse continue to live with all of us,” Biles said. “I worked incredibly hard to make sure that my presence could help maintain a connection between the failures [around the Nassar case] and the competition at Tokyo 2020.
“To be clear, I blame Larry Nassar and I also blame an entire system that enabled and perpetrated his abuse.
“USA Gymnastics and the United States, Olympic and Paralympic Committee knew that I was abused by their official team doctor long before I was ever made aware of their knowledge.”
Biles is one of a number of Olympians who allege abuse by Nassar, who was sentenced to 60 years in federal prison in December 2017.
Gold medallists Aly Raisman and McKayla Maroney also spoke at Tuesday’s hearing into the FBI’s failed 2015 investigation into the case.
Nassar was fired by his primary employer, Michigan State University, after a police report was filed against him in 2016.
However an investigation from the US Justice Department found that Nassar was able to abuse up to 70 athletes between the time the FBI first learned of the allegations and his dismissal from Michigan State.
“Nassar is where he belongs,” Biles continued at the hearing.
“Those who enabled him deserve to be held accountable. If they are not, I am convinced that this will continue to happen to others across Olympic sports.
“I am a strong individual and I will persevere, but I never should have been left alone to suffer the abuse of Larry Nassar. And the only reason I did, was because of the failures that lie at the heart of the abuse that you are now asked to investigate.”
USA Gymnastics has announced a plan to pay a $215m (£164m) settlement to the athletes abused by Nassar.
“Children suffered needlessly because multiple agents in multiple offices at the FBI neglected to share the Nassar allegations with their law enforcement counterparts at state and local agencies,” Chuck Grassley, a Republican senator, said in prepared remarks before the hearing.