Fans at the Australian Open can wear "Where is Peng Shuai?" shirts as long as they are peaceful, tournament chief Craig Tiley told AFP Tuesday, after a backlash over the Grand Slam's controversial stance.

The about-turn followed video emerging on Sunday of security staff ordering spectators to remove shirts and a banner in support of the Chinese player at Melbourne Park.

It prompted tennis legend Martina Navratilova to brand the move "pathetic".

Peng, the former doubles world number one is absent from Melbourne and there are fears for her wellbeing after she alleged online in November that she had been "forced" into sex by a Chinese former vice-premier during a years-long on-and-off relationship.

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 free.

Tennis Australia, which organises the Australian Open, reiterated its long-standing policy on Monday of "not allowing banners, signs or clothing that are commercial or political".

But with pressure mounting, Tiley said "Where is Peng Shuai?" T-shirts would be permitted as long as those wearing them were peaceful, adding that security would make case-by-case assessments.

"Yes, as long as they are not coming as a mob to be disruptive but are peaceful," he told AFP on the sidelines of the Grand Slam.

"It's all been a bit lost in translation from some people who are not here and don't really know the full view.

"The situation in the last couple of days is that some people came with a banner on two large poles and we can't allow that.

"If you are coming to watch the tennis that's fine, but we can't allow anyone to cause a disruption at the end of the day."

A GoFundMe page set up to raise money to print more T-shirts reached its Aus$10,000 (US$7,100) goal within two days, with activists pledging to make them available to whoever wants to wear them.

Relaxation of the policy came as local media cited human rights experts as saying Tennis Australia's stance could be unlawful.

"There does not appear to be any proper basis for asking an attendee to remove a T-shirt that highlights a human rights issue," barrister Michael Stanton told The Age newspaper.

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.

Leading players at the Australian Open have on several occasions said they still hope to hear from Peng so they can be assured of her safety.

Tiley reiterated that "our main concern is the welfare of Peng Shuai and we have worked closely with the WTA".

"We encourage her to have direct conversations. The most appropriate people to do that with is the WTA."