Nov 18 (Reuters) - The International Tennis Federation (ITF) is committed to player safety and supports an investigation into the whereabouts of Chinese player Peng Shuai, the governing body said on Thursday. Former doubles world number one, Peng, 35, hasn"t been seen or heard from publicly since she said on social media that a former vice-premier of China, Zhang Gaoli, coerced her into sex and that they later had an on-off consensual relationship.Her post was deleted about half an hour later. "Player safety is always our top priority and we support a full and transparent investigation into this matter," the ITF said in a statement to Reuters. Women"s Tennis Association (WTA) chairman Steve Simon expressed doubt over an email the association received on Wednesday in which Peng, a Grand Slam winner in women"s doubles, denied the allegations of sexual assault. read more The email, released by Chinese state media outlet CGTN, quoted Peng as saying: "I"m not missing, nor am I unsafe. I"ve just been resting at home and everything is fine." Simon said he had a "hard time believing" that Peng actually wrote the email herself. "The statement released today by Chinese state media concerning Peng Shuai only raises my concerns as to her safety and whereabouts," he said in a statement. "The WTA and the rest of the world need independent and verifiable proof that she is safe. I have repeatedly tried to reach her via numerous forms of communication, to no avail." Simon"s demands were backed by rights group Amnesty International, which said that China must prove Peng is safe. "Peng"s recent so-called statement that "everything is fine" should not be taken at face value as China"s state media has a track record of forcing statements out of individuals under duress, or else simply fabricating them," said Amnesty"s China researcher, Doriane Lau. "These concerns will not go away unless Peng"s safety and whereabouts are confirmed." The International Olympic Committee said it would not comment on the matter. "Experience shows that quiet diplomacy offers the best opportunity to find a solution for questions of such nature," an IOC spokesperson said. "This explains why the IOC will not comment any further at this stage." Peng is a three-time Olympian, having competed at the Beijing 2008 Games and well as in the London 2012 and the Rio de Janeiro 2016 editions. Reuters reached out to the Chinese Tennis Association but did not immediately receive a response. There has been mounting concern for Peng among fellow players, with four-times major winner Naomi Osaka and men"s world number one Novak Djokovic both expressing shock. "Censorship is never ok at any cost. I hope Peng Shuai and her family are safe and ok. I"m in shock of the current situation and I"m sending love and light her way," Osaka wrote on Twitter.