Olympic phenomenon Simone Biles says she was also sexually assaulted by Team USA gymnastics doctor Larry Nassar.

One of the stars of the Rio 2016 games, with four gold medals and a bronze, Biles is the latest athlete to come forward with allegations against Nassar.

"I too am one of the many survivors that was sexually abused by Larry Nassar," Biles, 20, said in a statement.

"Please believe me when I say it was a lot harder to first speak those words out loud than it is now to put them on paper.

"There are many reasons that I have been reluctant to share my story, but I know now it is not my fault.

"This behaviour is completely unacceptable, disgusting, and abusive, especially coming from someone whom I was TOLD to trust.

"As I continue to work through the pain, I kindly ask everyone to respect my privacy. This is a process, and one that I need more time to work through."

In November, Nassar pleaded guilty to abusing seven girls, mostly under the guise of treatment at his Lansing-area home and a campus clinic, while he was working at USA Gymnastics and Michigan State University.

He was sentenced in December to 60 years in federal prison for possessing child pornography and is facing another 40 to 125 years in prison for assaulting the seven girls.

Nassar lost his licence to practice medicine in April last year.

Of his more than 100 accusers, all but one was a gymnast, with Olympians McKayla Maroney, Aly Raisman and Gabby Douglas among the women to publicly say they were among Nassar's victims.

Biles endured one of the most heartbreaking moments of the Rio Games in 2016 when her foot slipped off the balance beam, dashing her hopes of leaving Rio with a record haul of five golds for a female gymnast.

She rebounded the next day though, winning gold in the floor routine the next day to go with her victories in all-round, team and vault competition.

Despite her slip, she also won bronze on the beam.

In October, two-time Olympic medallist Maroney became the highest-profile gymnast at that time to level allegations at Nassar.

Maroney, now 21, said the abuse began when she was 13 while attending a US national team training camp in Texas and continued for the rest of her competitive career.

She said Nassar told her she was receiving "medically necessary treatment he had been performing on patients for over 30 years". She did not detail Nassar's specific actions.

She described Nassar giving her a sleeping pill while the team travelled to Japan for the 2011 world championships.

She said Nassar later visited her in her hotel room after the team arrived in Tokyo, where he molested her yet again.

Biles has been an elite gymnast since 2011, and after taking a break to enjoy life away from the gym, she is now training and planning to make her return at the US Classic in late July with the goal of competing in the 2020 Tokyo Olympics.