A sports psychologist represented by Norton Rose Fulbright is suing the U.S. Olympic Committee, claiming its members silenced and discredited him when he tried to shine a light on sexual abuse against athletes.

Dr. Steven Ungerleider alleges the USOC and board member Angela Ruggiero defamed and retaliated against him after learning last autumn he was assembling a commission to draw attention to sexual abuse. According to the lawsuit filed Friday in Boston federal court, Ungerleider had spoken with more than 100 athletes who said they were abused by coaches, doctors or others involved in their training.

Ungerleider claims Ruggiero, an Olympic medalist in ice hockey who leads the Boston-based Sports Innovation Lab, called him “a liar and a fraud who was manipulating young women into making false allegations of sexual abuse,” according to the plaintiff's attorney, Thomas McCormack of Norton Rose Fulbright in New York. After receiving a cease-and-desist letter from Ungerleider, Ruggiero denied making defamatory comments.

Ruggiero and the rest of the committee then cut all ties with Ungerleider, including removing the USOC accreditation that brought him most of his counseling clients, the lawsuit alleges.

“As a longtime part of the Olympic Movement, Dr. Ungerleider tried for years to convince the USOC to address the longstanding sexual abuse problem that only recently gained national attention,” McCormack wrote in a statement. “But rather than working to prevent sexual abuse, the USOC instead treated it as a public relations problem that needed to be contained.”

Through an attorney, Ruggiero denied the allegations.

“As Dr. Ungerleider was informed prior to his ill-advised decision to file this lawsuit, his claims are frivolous and will be vigorously defended,” said Ruggiero's attorney, Michael Grygiel of Greenberg Traurig in Albany, New York. “The complaint's allegations are pulled out of thin air and have no basis in reality, and Ms. Ruggiero is confident in her ability to demonstrate the same in defending this case.”

The committee did not immediately respond to requests for comment.

The lawsuit comes two months after Dr. Larry Nassar was sentenced to life in prison for sexually abusing at least 150 gymnasts, including Olympians Simone Biles, Gabby Douglas, McKayla Maroney, Aly Raisman and Jordyn Wieber. Maroney and Raisman have each filed lawsuits alleging the USOC worked with USA Gymnastics to silence victims and cover up Nassar's abuse.

USA Swimming is also facing allegations of ignoring widespread sexual abuse against athletes after an investigation published last month by Southern California News Group.

Ruggiero was appointed in 2013 to the USOC's SafeSport task force, a group devoted to rooting out misconduct in sports, including sexual abuse.

“While the resources developed by the USOC are fantastic, and the pro bono legal support provided has been amazing, we can always do more to ensure that children are protected and sport organizations are thriving,” Ruggiero said in a statement at the time.

But Ungerleider alleges Ruggiero was also motivated to protect the USOC's image because of her role on a committee that aims to bring the Olympics to Los Angeles. The sports psychologist claims that after he began convening his commission late last year, four different people associated with the Olympics that he knows told him Ruggiero had disparaged him and his efforts.

Grygiel said Ruggiero “stands with the survivors and unreservedly supports full transparency in the investigation of sexual abuse cases involving USA Gymnastics — or any other athletic program or organization — and the legal prosecution of those responsible.”

Along with McCormack, Ungerleider's legal team also includes Norton Rose Fulbright attorney Michael Bhargava. Boston counsel for the plaintiff is Meredith Leary of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo.

The case was assigned to District Judge Jennifer Boal.