The U.N. and White House have joined the growing demand for assurances and proof that missing Chinese tennis champ Peng Shuai is safe. 

Peng, 35, wrote a post on Weibo, a Chinese social media platform, alleging sexual abuse she suffered at the hands of China's former vice-premier Zhang Gaoli. Peng claimed Zhang, 75, forced her to have sex despite repeated refusals following a round of tennis three years ago. 

The post was quickly deleted and Peng has since disappeared from social media and public view. Tennis players and officials, led by Women’s Tennis Association CEO Steve Simon, are demanding a full investigation into Peng’s claims as well as assurances of her safety and wellbeing. 

Peng Shuai's disappearance may be part of President Xi Jinping's cultural crackdown.

Peng Shuai's disappearance may be part of President Xi Jinping's cultural crackdown. (Getty Images)

U.N. and White House officials have joined the growing demand for clear evidence of Peng’s safety after China’s state-owned TV outlet CGTN last week posted an email it claimed Peng sent Simon, which Simon said only further raised concerns and doubts about Peng’s safety. 

"It would be important to have proof of her whereabouts and wellbeing," U.N. Human Rights spokesperson Liz Throssell told reporters Friday. "We would urge that there be an investigation with full transparency into her allegations of sexual assault." 

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"It is really important to ensure accountability and justice for the victims, people who have suffered terrible trauma," she added. 

White House press secretary Jen Psaki echoed Throssell’s sentiment during a Friday press briefing, saying, "We are deeply concerned by reports that Peng Shuai appears to be missing." 

White House press secretary Jen Psaki speaks with reporters in the James Brady Press Briefing Room at the White House, Friday, Nov. 19, 2021, in Washington.

White House press secretary Jen Psaki speaks with reporters in the James Brady Press Briefing Room at the White House, Friday, Nov. 19, 2021, in Washington. (AP Photo/Alex Brandon)

"We would join in the calls for PRC authorities to provide independent, verifiable proof of her whereabouts and that she is safe," Psaki told reporters. "I can’t speak, of course, to the details of the case or any more detail of where she might be, but … any report of sexual assault should be investigated." 

Psaki noted Beijing’s "zero tolerance for criticism" and "a record of silencing those that speak out," which the White House will "continue to condemn." 

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Deputy Secretary of State Wendy Sherman tweeted: "We are deeply concerned by reports that tennis player Peng Shuai appears to be missing, and we join the calls for the PRC to provide independent, verifiable proof of her whereabouts. Women everywhere deserve to have reports of sexual assault taken seriously and investigated."

Biden recently told reporters he is considering a "diplomatic boycott" of the 2022 Winter Olympics in Beijing due to a number of issues between the U.S. and China, includding China's treatment of ethnic minorities. In such a move, the U.S. would not send an official government delegation to the Olympics, but athletes would still compete.

Ministry spokesperson Zhao Lijian. 

Ministry spokesperson Zhao Lijian.  (AP Photo/Andy Wong, File)

Sen. Marsha Blackburn, R-Tenn., told Fox News that Biden needs to do more to address Peng’s situation. 

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"In light of tennis star Peng Shuai’s disappearance, it has become increasingly apparent that the safety and security of Team USA athletes cannot be guaranteed at the 2022 Beijing Olympics," Blackburn said. "That is why I’m calling on the United States Olympic Committee to refrain from sending American athletes to the 2022 Olympics."

Despite the growing international pressure and the WTA’s threat to pull tournaments from China unless the situation is satisfactorily resolved, Beijing continues to maintain that it is "unaware" of Peng’s situation. 

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Ministry spokesman Zhao Lijian told reporters Friday the matter was "not a diplomatic question, and I’m not aware of the situation" – a stance he has maintained whenever a reporter asks about Peng. 

The Associated Press contributed to this report.