Jessica Howard, the US national rhythmic gymnastics champion from 1999 to 2001, and Jeanette Antolin, an Pan American Games silver medallist, were speaking in a preview of a CBS television  60 Minutes programme due to be broadcast tomorrow.

Howard detailed to CBS an appointment with Nassar at the USA Gymnastics National Team Training Centre at Karolyi Ranch in Houston in Texas.

"He started massaging me and he had asked me not to wear any underwear and then he just continued to go into more and more intimate places," said the 32-year-old, who is now a stretch and conditioning specialist working for several ballet companies. 

"I remember thinking something was off, but I didn't feel like I was able to say anything because he was this very high profile doctor and I was very lucky to be at the ranch working with him.

"The girls would say 'Yeah, he touches you funny'."

Antolin was on the US team from 1995 to 2000 and a member of the 1999 World Championship squad and is now 35.

She also recalled an encounter with Nassar.

"I remember being uncomfortable because of the area, but, in my mind, I was like, 'If this helps, I'll do anything'," Antolin, a member of the US squad that won Pan American Games silver medals at Winnipeg in 1999, said.

"It was treatment.

"You don't complain about treatment."

A third woman who spoke with CBS was not identified in promotional material for the broadcast.

Nassar was arrested in December as part of a Federal investigation into child pornography.

He is accused of molesting dozens of patients during his time in the role from 1996 until 2015.

Nassar is alleged to have possessed "thousands of images of child pornography" between 2003 and 2016, according to a two-count indictment filed in Michigan.

John Manly, a California attorney representing more than 40 women in a lawsuit against USA Gymnastics for failing to protect his clients, claimed that Nassar may have abused hundreds of women over more than two decades.

"We know that at least 60 have come forward, but my best estimate is it's in the hundreds and possibly more," Manly told CBS.

"I believe that at the end of the day, there are members of every single Olympic team since 1996 he did this to."

An investigation undertaken by the Indianapolis Star claimed that "at least" 368 American gymnasts have made allegations of sexual abuse in the past 20 years.

USA Gymnastics declined to speak with the programme on camera.

The organisation claims it severed ties with Nassar in 2015 when first learning of the testimonies against him.