The International Olympic Committee was under siege.

Peng Shuai, a three-time Olympian from China, had not been heard from for weeks after making sexual abuse allegations against a senior political official, a man who had played a central role in preparations for the coming Winter Games in Beijing.

Initially silent on the disappearance of Peng, a women’s tennis star, Olympic officials were now facing a growing global chorus of concern. The WTA Tour, through its chief executive, was demanding answers and an investigation. Fellow tennis stars like Serena Williams and Naomi Osaka — but also human rights groups, politicians and everyday fans — were using social media to ask #WhereIsPengShuai? Media organizations were flooding the internet with news coverage.

Cornered by the criticism, the I.O.C. finally responded. This, Olympic officials insisted, was a time not for public statements but for “quiet diplomacy.”

For the organization’s many critics, the guarded, cautious language — viewed more as an attempt to explain away its silence rather than ensure Peng’s safety — was just the latest proof that the I.O.C. will not take any action that might upset China’s government, its partner for a Winter Olympics that is now only months away.

The response drew public condemnation and frustration behind the scenes in the Olympic movement.

“The I.O.C. must not be complicit in protecting the regime and allowing it be captured for Chinese propaganda purposes,” said Maximilian Klein, the head of international relations for Athleten Deutschland, a representative group for German athletes.

Many national Olympic committees, facing pressure at home to speak out more forcefully on China’s human rights record, are now grumbling about what they feel is a failure of leadership by the I.O.C. Some fear that the unwillingness of Olympic leaders to challenge or pressure China has left them, and their athletes, exposed to possible retribution during the Games.

“In absence of them saying something, it shifts pressure to others to do so,” said one national Olympic committee official, who declined to be quoted by name out of fear of making an uncomfortable situation worse. “If we start being critical, all of a sudden it becomes more political if a nation starts to criticize China.”

“We are the ones that need to keep our heads down,” the official added, “not the I.O.C.”

The efforts of top Olympic officials to clarify Peng’s status have done little to ease the crisis of confidence. On Sunday, the I.O.C. released an image of a video call involving Peng and Thomas Bach, the I.O.C. president. The call was the first known contact between the tennis player and a Western sports official since she went public with her sexual assault allegations, and since China, which once hailed her successes in state media, quickly deleted them and then moved to erase any mention of her accusation.

Rather than assuage concerns, though, the call only raised more questions about the relationship the I.O.C. enjoys with China’s government.

The I.O.C. statement accompanying the image provided scant details of what was discussed during the 30-minute meeting with Peng, 35, and it conspicuously avoided reference to the sexual assault allegations against Zhang Gaoli, a former vice premier of China who retired in 2018. Zhang was vice premier when Beijing was awarded the Winter Olympics in 2015, and he led an organizational committee that oversaw preparations. In 2016, he met Bach during a visit to China.

In the single image released by the I.O.C., Peng is smiling broadly in a room filled with plush toys, including mascots from previous Olympics. The I.O.C. statement said Bach ended the call by suggesting he and Peng try to meet for dinner when he arrives in Beijing in January. The committee did not release any audio or transcript of what Peng said in her own words or suggest Bach or anyone else asked her about her sexual assault claims.

“To just kind of whitewash the whole thing — ‘Nothing to see here!’— is generally problematic,” said Sarah Cook, the director of research for China at Freedom House, a rights organization based in Washington, D.C., referring to the I.O.C.’s handling of the case and its relationship generally with the Olympic hosts. “Collaborating with the Chinese government to suppress people’s rights is different than anything that has been done before.”

Richard Pound, a Canadian lawyer and the I.O.C.’s longest-serving member, defended the organization’s tactics — and took aim at its critics — in an interview last week.

“What the I.O.C. established is that quiet and discreet diplomacy gets you better than clashing cymbals,” Pound said. “That’s not the way you deal with any country, certainly not with China.”

It is unclear how Bach managed to engineer a call with Peng when the WTA Tour and others had been unsuccessful, though the presence on the call of an I.O.C. member from China, Li Lingwei, offered a tantalizing clue.

“The I.O.C. has vaulted itself from silence about Beijing’s abysmal human rights record to active collaboration with Chinese authorities in undermining freedom of speech and disregarding alleged sexual assault,” said Yaqiu Wang, a senior China researcher at Human Rights Watch. “The I.O.C. appears to prize its relationship with a major human rights violator over the rights and safety of Olympic athletes.”

Teng Biao, a lawyer and prominent human rights campaigner who was detained in 2008 for criticizing China’s preparations for that year’s Summer Olympics, said it was illogical that Peng would have organized a call with Bach by herself. In a telephone interview from his home in New Jersey, where he now lives in exile, Teng suggested the authorities in Beijing had set up the call with Bach rather than risk one between Peng and a critic like the WTA Tour chief executive, Steve Simon, who has pressed China publicly to allow Peng to move and speak freely.

When it comes to the Olympics in Beijing, Teng said, “The I.O.C. and Bach are not neutral.”

For Bach, a pragmatist, there has been little room to maneuver once China secured hosting rights to the 2022 Winter Games six years ago amid a dearth of suitable candidate cities. The Olympics generate 91 percent of the organization’s income, so the I.O.C. has long avoided doing anything that might put at risk those billions of dollars in revenue.

“Thomas Bach is all about protecting the Olympics,” Adam Pengilly, a former I.O.C. member, said in explaining how Bach, formerly a gold-medal-winning fencer, has moved to secure the future of the Games since assuming the presidency in 2013.

During his tenure, crucial long-term television agreements have been completed, and rules were changed to appoint Paris and Los Angeles hosts for the next two Olympics without competition. Then a small committee was empowered to streamline the process even further, effectively delivering the 2032 Summer Games to Brisbane, Australia, the home nation of the committee’s leader, before any other city could bid.

“He would justify that by saying, ‘I think this is the best way to protect the Olympics,’” Pengilly said of Bach. “When that’s your starting point, then you bring yourself into difficulties when stuff like this happens.”

The I.O.C. has wrestled with thorny questions about China’s human rights record for years. In 2008, when Beijing hosted the Summer Games, the I.O.C. adopted a public relations posture that the greater scrutiny the Olympics bring would ultimately yield positive changes within Chinese society.

Yet since then, the opposite has happened. While in 2008 the focus was largely on China’s policies in Tibet, its government now also faces criticism of its crackdown on political freedoms in Hong Kong, the semiautonomous territory, and its repression in the Xinjiang region, where hundreds of thousands of Uyghurs and other Muslims have been detained in a campaign that the United States has called genocidal.

Tarred as complicit in human rights violations, the I.O.C. that once suggested it could change China by giving it the Games has more recently argued that it can control only what happens inside the Olympic bubble.

“The International Olympic Committee, as a civil nongovernmental organization, is strictly politically neutral at all times,” Bach wrote last year in a column published by The Guardian. “Neither awarding the Games, nor participating, are a political judgment regarding the host country.”

Christophe Dubi, the most senior I.O.C. official responsible for the Olympics, insisted human rights clauses were included in its contract with Beijing, though Peng’s case appears to fall outside that agreement.

“What is outside the contract is a different story, but we act where we have a contract and there we are very clear,” Dubi told The New York Times this week.

“I follow what is going on,” Dubi added, “and am I happy that the I.O.C. is being criticized? No, I am not happy that the I.O.C. is being criticized. I am not happy when I hear and read some of the stories.”

Dubi insisted that no subject would be off limits to the news media attending and covering the Games, but whether there will be answers remains unclear. Chinese officials pressed about Peng initially claimed ignorance even as the story drew worldwide attention, and, like the I.O.C., the Chinese government still has not commented on the sexual assault allegations.

The Olympic committee’s light-touch response to them, though, may have ensured that nothing will derail the final push toward the opening ceremony in Beijing in less than 100 days.

“It does not encroach on anything I’m doing at my level to deliver the Games,” Dubi said.