The U.N. office for human rights requested information over the whereabouts of Chinese tennis star Peng Shuai on Friday (November 19).
U.N. human rights spokesperson, Liz Thorssell:
"We would stress that it is important to know where she is and you know, her state, know about her well being. And as I said, we think it would be important that there is an investigation into her allegations of sexual assault. "
Former doubles world number one Peng has not been seen or heard from publicly since she said on Chinese social media on November 2 that former vice-premier Zhang Gaoli coerced her into sex, and they later had an on-off consensual relationship.
Neither Zhang or the Chinese government have commented on her allegation.
Peng's social media post was quickly deleted and the topic has been blocked from discussion on China's heavily censored internet.
Concerns among the global tennis community and beyond has grown over Peng's safety.
The Women's Tennis Association - or WTA- is calling for an investigation and said it was prepared to pull its tournaments - worth tens of millions of dollars - out of China over the issue.
On Wednesday (November 17) WTA Chief Executive Steve Simon said he had received an email purporting to be from Peng and denying the allegations of sexual assault - but he cast doubt over the veracity of the email.
A Chinese state media outlet also released the letter on Twitter.
Hu Xijin, an influential China state media editor, weighed in on the scandal on Twitter earlier on Friday, saying he does not believe Peng has been the target of retribution.
Some of the world's top tennis players, including Naomi Osaka and Serena Williams have tweeted #WhereIsPengShuai.
The hashtag has racked up over 32 million mentions on Facebook's Instagram and Twitter, according to website Brandmentions.
Both platforms are blocked in China.