The head of the Women's Tennis Association Steve Simon has said he is willing to lose hundreds of millions of dollars worth of business in China if tennis player Peng Shuai's safety is not fully accounted for and her allegations are not properly investigated.

"We're definitely willing to pull our business and deal with all the complications that come with it," Simon said in an interview Thursday with CNN. "Because this is certainly, this is bigger than the business," added Simon.

"Women need to be respected and not censored," said Simon.

Peng, who is one of China's most recognizable sports stars, has not been seen in public since she accused former Vice Premier Zhang Gaoli of coercing her into sex at his home, according to screenshots of a since-deleted social media post dated November 2.

Her post on Weibo, China's Twitter-like platform, was deleted within 30 minutes of publication, with Chinese censors moving swiftly to wipe out any mention of the accusation online.

Her Weibo account, which has more than half a million followers, is still blocked from searchers on the platform.

In the early hours of Wednesday morning local time, China's state-owned television broadcaster CGTN released an email, purportedly from Peng and sent to Simon, walking back her sexual allegations and claiming she is fine.

When asked about the email, Simon questioned its veracity, describing it as a "staged statement of some type."

"Whether she was coerced into writing it, someone wrote it for her, we don't know. But at this point I don't think there's any validity in it and we won't be comfortable until we have a chance to speak with her," he added.

On Thursday, Serena Williams joined a growing number of international tennis players to voice concern over Shuai's whereabouts.

"I am devastated and shocked to hear about the news of my peer, Peng Shuai. I hope she is safe and found as soon as possible," Williams said. "This must be investigated and we must not stay silent. Sending love to her and her family during this incredibly difficult time."

This is a developing story, more to come.