(CNN) Simone Biles reacted Thursday to a Wall Street Journal report accusing USA Gymnastics of ignoring the possibility she had been sexually abused by Larry Nassar and excluding her from the investigations of the national team's now-disgraced doctor.

"Can't tell you how hard this is to read and process," Biles, gymnastics' preeminent star, wrote in a tweet sharing the WSJ story . "The pain is real and doesn't just go away ... especially when new facts are still coming out."

"What's it going to take," she asked, "for a complete and independent investigation of both (the US Olympic and Paralympic Committee) and USAG?"

Can't tell you how hard this is to read and process. The pain is real and doesn't just go away...especially when new facts are still coming out. What's it going to take for a complete and independent investigation of both USOPC and USAG??? https://t.co/UrDXIrTng9

According to the WSJ report, USAG, the sport's governing body in the US, withheld the investigation of the doctor's sexual abuse from Biles -- despite the fact she was among the first athletes USAG learned were uncomfortable with the doctor.

Then-CEO Steve Penny, who left USAG in 2017 , was aware of Biles' concerns, the report says, but he did not include her in a weeks-long internal investigation of Nassar and did not mention her when he spoke to the FBI.

All of this took place as USAG became increasingly invested in Biles' status as the sport's biggest athlete, with Penny once suggesting that USAG try to become her agent, according to the WSJ. And when USAG approached the FBI in Indianapolis in 2015, the WSJ reports, Biles was in town doing promotional appearances that included attending a party for Penny's daughter's gymnastics group.

The WSJ says its report is based on interviews with "key participants;" comments by Penny's lawyers; documents provided to the US Senate Commerce Committee; and a report by Ropes and Gray, a law firm commissioned by the US Olympic and Paralympic Committee.

Per the WSJ, Biles didn't learn of the FBI investigation until she came home from the 2016 Olympics in Rio de Janeiro, where she won four gold medals. It wasn't until 2018, when Biles revealed that she, too, had been abused by Nassar, that a USAG official asked her about the team doctor, the WSJ report says, citing people familiar with the matter.

Nassar, once a celebrated sports physician for the USA Gymnastics national team and Michigan State University, is spending the rest of his life in prison . He pleaded guilty to federal child pornography charges and state charges of criminal sexual conduct stemming from the sexual abuse of patients under the pretense of providing medical treatment.

More than 150 women and girls said in court that he sexually abused them over the past two decades.

In a statement, current USAG President and CEO Li Li Leung said the organization was "surprised, deeply saddened and outraged to learn from the Wall Street Journal that Simone Biles was one of the athletes mentioned in the original notification in 2015 that triggered the initial Nassar investigation."

"We have extended our apologies to Simone and her family," Leung said, "and we are very sorry our organization's leadership at the time handled this situation in a disrespectful and inconsiderate way."

CNN has reached out to USOPC and Biles' family for comment.

'It feels like the harshest of betrayals'

A statement released by Penny's attorneys said he was "dismayed by the lack of effort made by law enforcement to address concerns regarding Nassar," adding he "regrets that any athlete experienced the slightest level of discomfort or abuse under Nassar's care."

"Mr. Penny did not know that Ms. Biles was a victim of Larry Nassar until Ms. Biles released her survivor statement on Twitter," the statement said. "Mr. Penny is not aware of Ms. Biles reporting to USA Gymnastics concern that she was uncomfortable with Nassar before USA Gymnastics went to the FBI."

Penny's attorneys said USAG had been instructed to not discuss the matter with other athletes at the time, but the organization had notified the FBI that there were additional athletes who could be helpful to its investigation.

Penny's comment about USAG becoming Biles' agent was "tongue in cheek," the attorneys told the WSJ.

According to the WSJ, the new head of the US women's gymnastics program at the time, Rhonda Faehn, was told in June 2015 that gymnast Maggie Nichols said Nassar massaged her groin, and that Biles and Aly Raisman, another acclaimed gymnast, also had concerns about him.

The WSJ reported that Faehn, who took notes and wrote down Biles' and Raisman's names, says she called Penny that night to tell him. Penny's attorneys said Faehn did not tell him about Biles at that time. Penny did acknowledge that he knew by mid-July that the USAG was aware it "might want to talk" to Biles about Nassar, the WSJ report says. Penny would not say how or when he learned that.

The law firm Ropes and Gray, which conducted an independent, 10-month-long investigation of USAG's handling of the Nassar case, noted in its report that on June 17, 2015, Faehn was provided the names of three gymnasts not named in the report who had concerns about Nassar.

Two of them "may have experienced 'the uncomfortable factor' with Nassar," the report says, adding Faehn "immediately relayed this information" to Penny, "who stated that he would handle the matter and notify the proper authorities."

One of those two athletes has since publicly identified herself as a survivor of Nassar's abuse, the Ropes and Gray report says, but there is no evidence that she "was ever contacted ... for an interview" by USAG.

"It is unconscionable -- and illegal -- that officials purporting to be leaders in sport knowingly hid reports of child sexual abuse," lawyers representing over 200 survivors of Nassar's abuse said in a statement obtained by CNN.

"We demand accountability for the safety and well-being of athletes at the 2020 Olympic Games and encourage all sponsors to stand with survivors and insist on reform," the lawyers said.

Biles declined to be interviewed for the WSJ's story, but her parents, Ron and Nellie Biles, told the paper the family still wrestles with the fallout of the abuse.

"We continue to struggle with how and why this happened, and every time we hear something new like this, it feels like the harshest of betrayals and it is just too painful for our family to talk about openly," they said in a statement. "To this day, we still do not know why Simone's abuse was concealed by Steve Penny, USAG and USOPC."