Australian Open organizers said Sunday that Peng Shuai's safety "is our primary concern" after video emerged of security staff preventing spectators wearing T-shirts in support of the Chinese player.
The former doubles world number one is absent from the Grand Slam and there are fears for her well-being after she alleged online in November that she had been sexually assaulted by a Chinese former vice-premier.
Her allegation was quickly censored and the 36-year-old was not heard from for nearly three weeks, before reappearing in public in China. But there are still concerns as to whether she is really free.
Leading players at the Australian Open have on several occasions said they still hope to hear directly from Peng so they can be assured of her safety.
However, a video posted online appears to show a firm line being taken against people at Melbourne Park wearing T-shirts saying "Where is Peng Shuai?"
The question has been used widely as a viral hashtag on Twitter, including by top players, to spread the word about Peng's apparent predicament.
The footage also appears to show Australian Open staff removing a banner.
"Under our ticket conditions of entry we don't allow clothing, banners or signs that are commercial or political," said a spokesperson for Tennis Australia, who organize the Grand Slam.
"Peng Shuai's safety is our primary concern," Tennis Australia added.
"We continue to work with the WTA and global tennis community to seek more clarity on her situation and will do everything we can to ensure her well-being."
The Women's Tennis Association has been widely praised for its stance on Peng, demanding to hear from her directly and suspending tournaments in China.