"This must be investigated and we must not stay silent" - Serena Williams on Peng Shuai's disappearance

Serena Williams has become the latest in a growing list of high-profile personalities to voice concerns about Peng Shuai's safety.

Peng, a former doubles No. 1, has been facing censorship in China after accusing the country's former Vice Premier Zhang Gaoli of sexual abuse. The Chinese player has not made any public appearances since she first came forward with her ordeal in a now-deleted Weibo post.

Steve Simon, chairman and CEO of the WTA, expressed concern about Peng Shuai's safety on Wednesday after receiving a suspicious letter attributed to the Chinese. Other members of the tennis fraternity, including Billie Jean King, Martina Navratilova, Alize Cornet, Novak Djokovic and Naomi Osaka, have also come out in support of Peng, as have journalists and social media users.

Peng Shuai hasn't made any publuic appearance since first coming forward with her ordeal.

Serena Williams, who has played Peng Shuai thrice on the WTA tour, expressed her shock at the news in a lengthy Twitter post. The 40-year-old urged people to speak out on the issue, before batting for an investigation into Peng's allegations.

"I am devastated and shocked to hear about the news of my peer, Peng Shuai," Serena wrote on Twitter. "I hope she is safe and found as soon as possible."

"This must be investigated and we must not stay silent," the American added. "Sending love to her and her family during this incredibly difficult time. #whereispengshuai"

#WhereIsPengShuai trending on Twitter as tennis icons press for answers

Peng Shuai (R) and Hsieh Su-wei at the 2014 WTA Finals,

Members of the tennis fraternity, journalists and the general public have taken to various social media platforms to express their support for Peng Shuai.

The #WhereisPengShuai hashtag was trending on Twitter globally on Thursday evening, with around 60,000 tweets. The WTA's official handle also shared a portrait of Peng Shuai with the same hashtag, which was retweeted more than 2,600 times within the first hour.

Leading a long list of prominent tennis players to have shared social media posts in Peng Shuai's support were sisters Agenieszka and Urszula Radwanska, Kim Clijsters, Julia Goerges, Barbora Strycova, Maria Sakkari, Jennifer Brady, Nicholas Mahut, Varvara Lepchenko as well as the official handle of the Tennis Channel.

Clijsters lauded the WTA's strong stance on the issue and asked her fellow tennis players to "get behind" the governing body.

"Strong stand by WTA. All of us players, male and female, need to get behind this. We need to know she is safe!" Clijsters wrote.

Goerges, meanwhile, said that she was "deeply concerned" about the situation, before adding that she stood with the tennis community in ensuring that the voice of the victim "is not silenced".

"I am deeply concerned about the ongoing situation involving Peng Shuai. We live in a world where victims should not be silenced & I stand with the entire tennis community in saying, we want answers! #whereisPengShuai," Goerges wrote.