Olympic gold medalist Simone Biles and dozens of other women who say they were sexually assaulted by Larry Nassar are seeking more than $US1 billion from the FBI for failing to stop the sports doctor when it first received allegations against him.

There’s no dispute FBI agents in 2015 knew that Nassar was accused of assaulting gymnasts, but they failed to act, leaving him free to continue to target young women and girls for more than a year.

He pleaded guilty in 2017 and is serving decades in prison.

“It is time for the FBI to be held accountable,” said Maggie Nichols, a national champion gymnast at Oklahoma in 2017-19.

• Related: Gymnasts win settlement over abuse 

Under federal law, a government agency has six months to respond to the tort claims filed on Wednesday. Lawsuits could follow, depending on the FBI’s response.

The approximately 90 claimants include Biles, Aly Raisman and McKayla Maroney, all Olympic gold medalists, according to Manly, Stewart & Finaldi, a California law firm.

Separately, 13 claims were filed by others in April.

“If the FBI had simply done its job, Nassar would have been stopped before he ever had the chance to abuse hundreds of girls, including me,” said former University of Michigan gymnast Samantha Roy.

An email seeking comment was sent to the FBI.

Indianapolis-based USA Gymnastics told local agents in 2015 that three gymnasts said they were assaulted by Nassar, a team doctor.

But the FBI did not open a formal investigation or inform federal or state authorities in Michigan, according to the Justice Department’s inspector general, an internal watchdog.