The FBI is to be sued by some of the most prominent American gymnasts abused by Larry Nassar ©Getty Images

Gymnasts including four-time Olympic champion Simone Biles are suing the Federal Bureau of Investigation (FBI) for its mishandling of an investigation into disgraced doctor and convicted sex offender Larry Nassar.

A group of around 90 gymnasts, who all suffered abuse by Nassar and many say this happened after he was first reported to the FBI in 2015, are seeking more than $1 billion (£797 million/€931 million) in damages.

"It is time for the FBI to be held accountable," said Maggie Nichols, a world bronze medallist and world team champion with the United States from 2015.

The claimants include Biles, Aly Raisman and McKayla Maroney, all American Olympic gold medallists, according to the Manly, Stewart & Finaldi law firm.

The lawsuit comes two weeks after the Department of Justice decided not to prosecute two former FBI agents who mishandled a 2015 investigation into Nassar, who was able to assault dozens more women and girls for more than a year after the FBI was first alerted to the physician's crimes.

"My fellow survivors and I were betrayed by every institution that was supposed to protect us - the US Olympic Committee, USA Gymnastics, the FBI and now the Department of Justice," said Maroney in a statement.

"It is clear that the only path to justice and healing is through the legal process."

Simone Biles is the most gymnasts taking legal action against the FBI ©Getty Images
Simone Biles is the most gymnasts taking legal action against the FBI ©Getty Images

Nassar was not arrested until November 2016 and was later sentenced to at least 140 years in prison for first-degree criminal sexual conduct, receiving and possession of child pornography, as well as tampering with evidence.

From July 2015 until September 2016, he was still working at Michigan State University (MSU), only being removed from his position when Rachael Denhollander - a former gymnast - came forward to the Indianapolis Star about the abuse she suffered at Nassar's hands, leading to his arrest.

"If entities and individuals are not motivated by love and what is right, consequences must be in place to motivate change," Denhollander said today.

"The FBI's failure had devastating consequences for survivors. 

"Since they will not deal with it, we will. 

"Proud of these women."

Recent settlements for survivors include $500 million (£389 million/€463 million) from MSU and a $380 million (£296 million/€352 million) agreement with USA Gymnastics and the United States Olympic and Paralympic Committee.

Nassar is believed to have abused at least 330 women, including when he was a USA Gymnastics team doctor.