The chairman of the Women’s Tennis Association (WTA) has said he is worried over the safety of leading Chinese player Peng Shuai, who has gone missing after she alleged that a top Chinese political leader had forced her to have sex with him.
WTA chairman Steve Simon said he had been repeatedly trying to reach her via numerous forms of communication, to no avail.
He called for "independent and verifiable proof that she is safe".
Simon has raised doubts over the authenticity of an email, purportedly sent by Peng to him, which has been posted on Chinese state media.
Simon said that he had a "hard time believing" the email was written by Peng.
China’s state-run CGTN published a screenshot on Twitter of what it said was an email written by Peng to Simon and other WTA officials.
In the email, Peng purportedly claims that her earlier accusations of sexual abuse are "not true" and says she is "resting at home and everything is fine."
But doubts were quickly flagged about the language used in the purported email from Peng, which Twitter users noted had a cursor visible in the screenshot posted by CGTN.
Simon said he was struggling to believe it was authentic.
"The statement released today by Chinese state media concerning Peng Shuai only raises my concerns as to her safety and whereabouts," Simon wrote in a statement.
"I have a hard time believing that Peng Shuai actually wrote the email we received or believes what is being attributed to her," he added.
"Peng Shuai displayed incredible courage in describing an allegation of sexual assault against a former top official in the Chinese government," said Simon.
"Her allegation of sexual assault must be respected, investigated with full transparency and without censorship.
"The voices of women need to be heard and respected, not censored nor dictated to."
China has kept silent over growing concern for the tennis star.
The media post alleging the sexual assault which sent shock waves through the Communist country was deleted half an hour after it was published as China's internet is under strict censorship and any mention of the private lives of top leaders is not allowed.
According to a screenshot of her verified Weibo account late on Tuesday, Peng said that Zhang Gaoli, who became a member of the Politburo Standing Committee coerced her into sex and they later had an on-off consensual relationship.