A recent interview in which Peng Shuai denied accusing anyone of sexual assault has done little to address concerns about the Chinese player's safety, the Women's Tennis Association reaffirmed.
Peng, a former doubles world number one, told French newspaper L'Equipe that a social media post where she appeared to allege that a former Chinese vice premier, Zhang Gaoli, had sexually assaulted her, was a "huge misunderstanding".
"Sexual assault? I never said anyone had sexually assaulted me in any way," said Peng of the Weibo post, which was later deleted.
The post led the WTA to suspend tournaments in China and caused an international outcry about her wellbeing.
In a statement, WTA chairman and CEO Steve Simon said: "It's always good to see Peng Shuai, whether in an interview or attending the Olympic Games.
"However, her recent in-person interview does not alleviate any of our concerns about her initial post from November 2nd. To reiterate our view, Peng took a bold step in publicly coming forth with the accusation that she was sexually assaulted by a senior Chinese government leader.
"As we would do with any of our players globally, we have called for a formal investigation into the allegations by the appropriate authorities and an opportunity for the WTA to meet with Peng - privately - to discuss her situation.
"We continue to hold firm on our position and our thoughts remain with Peng Shuai."
International Olympic Committee president Thomas Bach met Peng over the weekend at the Beijing Winter Games, where the 36-year-old is set to attend a number of events.
"We said what we had to say, the communication is up to her, it is her life, it is her story and this is why the communication is up to her," Bach said.