Nassar, who appeared for a plea hearing at Ingham County Court in Lansing in Michigan, was given 20 years for each count.

He has also been charged with molesting seven girls during his time with the governing body and will be sentenced separately for this in January.

All but one of his accusers are gymnasts, while three of them were under the age of 13.

The offences, which occurred between 1998 and 2015, took place at his home and at his clinic in Michigan.

Olympic gold medallists Aly Raisman, McKayla Maroney and Gabby Douglas are among those to have accused the 54-year-old of sexual abuse when he served as the doctor for the American team.

Nassar, 54, is expected to serve at least 25 years in prison but could remain behind bars for 40 years.

Investigators revealed that they discovered more than 37,000 images of child sexual abuse in 2016 alone.

This included of children as young as six.

The sentence awarded by US District Judge Janet Neff in Grand Rapids, Michigan, was the highest available.

"There is a close link between the defendant's child-pornography activities and his prolific molestation of children," said Assistant US Attorney Sean Lewis, as reported by MLive.

"The seriousness of his conduct, and the devastating impact it has had on so many, cannot be overstated."

Defense lawyers said Nassar “deeply regrets the pain that he has caused the community".

Maroney described Nassar as a "monster" in an impact statement published before the sentencing. 

Nassar is a “monster” who “left scars on my psyche that may never go away,” Maroney said.

"He abused my trust, he abused my body and he left scars on my psyche that may never go away...

"He needs to be behind bars so he will never prey upon another child."

Over 130 women have also filed civil lawsuits alleging abuse against Nassar.