In delivering her verdict at the courthouse in Lansing in Michigan, Judge Rosemarie Aquilina said she had just signed Nassar's "death warrant".

Nassar was sentenced following an emotional hearing, where 156 girls and women accused him of abuse.

"It is my honour to sentence you because, sir, you do not deserve to walk outside of a prison ever again," Judge Aquilina said.

"Anywhere you walk, destruction would occur to those most vulnerable.

"I just signed your death warrant."

Nassar had pleaded guilty to the seven counts brought against him in Ingham County in November.

The 54-year-old still faces a further three counts in Eaton County, where his sentencing is scheduled to begin next week (January 31).

Nassar was sentenced to 60 years in jail in December for three counts relating to child sex abuse images on his computer.

In response to the sentencing, United States Olympic Committee (USOC) chief executive Scott Blackmun said an independent investigation would be launched "to examine how an abuse of this proportion could have gone undetected for so long".

The investigation will include both the USOC and USA Gymnastics and the results will be made public once it has been completed.

Three-time Olympic gold medallist Aly Raisman, one of those to deliver a victim statement during the sentencing hearing, was among those to criticise USA Gymnastics and the USOC for not investigating the abuse raised by athletes.

In an open letter, Blackmun said the USOC had "strongly considered decertifying USA Gymnastics as a National Governing Body" for their role in the scandal.

"But USA Gymnastics includes clubs and athletes who had no hand in this and who need to be supported," Blackmun added. 

"We believe it would hurt more than help the athletes and their sport. 

"But we will pursue decertification if USA Gymnastics does not fully embrace the necessary changes in their governance structure along with other mandated changes under review right now."

The USOC called on all current USA Gymnastics directors to resign after three of the leadership team stepped down earlier this week.

Chairman Paul Parilla, vice-chairman Jay Binder and treasurer Bitsy Kelley all resigned following the mounting criticism of their response.

Blackmun said "a full turnover of leadership from the past" was necessary, which means "all current USA Gymnastics directors must resign".

Blackmun also issued an apology for the Olympic family "failing" the athletes who suffered abuse by Nassar but admitted it was "not enough".

Judge Aquilina appeared to address the failures of the USOC and USA Gymnastics when she declared that there had to be a "massive investigation as to why there was inaction, why there was silence".

"Justice requires more than what I can do on this bench," she said.

The judge had also earlier read out a letter written by Nassar last week where he said it was too difficult for him to listen to the victim impact statements.

In the letter, written two months after he pleaded guilty, Nassar claimed he was treated unfairly and accused some of the victims for lying for media attention and financial reward.

"I was a good doctor because my treatments worked, and those patients that are now speaking out are the same ones that praised and came back over and over," Nassar wrote. 

"The media convinced them that everything I did was wrong and bad. 

"They feel I broke their trust. 

"Hell hath no fury like a woman scorned."

Nassar read out a brief statement of apology, in which he claimed the statements from those he abused had "shaken me to my core".

"There are no words that can describe the depth and breadth of how sorry I am for what has occurred," he said.

"An acceptable apology to all of you is impossible to write and convey. 

"I will carry your words with me for the rest of my days."

Japan's International Gymnastics Federation (FIG) President Morinari Watanabe said he was "shocked and saddened" when insidethegames asked the world governing body for comment.

"As I always said, the welfare and safeguarding of children and young athletes is fundamental to our sport," he said. 

"We will not tolerate any abuse or sexual harassment in the gymnastics community. 

"One of the very first measures I took as FIG President was to mandate a working group led by FIG honorary vice president Slava Corn to review and reinforce existing rules in this respect. 

"We welcome the International Olympic Committee's toolkit for the Olympic Movement to safeguard athletes from harassment and abuse in sport. 

"This documentation provides a solid base upon which to work. 

"The next step is the establishment of an independent body where any potential cases of abuse could be reported. 

"It will work closely with legal experts and recognised appropriate authorities."