Image source, Getty ImagesImage caption, Peng Shuai said she was "forced" to have sexual relations with former Vice-Premier Zhang Gaoli

One of China's top tennis players, Peng Shuai, has accused former Vice-Premier Zhang Gaoli of sexually assaulting her.

Since she posted the accusations on social media, there has been concern about the tennis star's whereabouts. On Sunday, the International OIympic Committee said it had spoken with Peng but questions about her wellbeing and safety remain.

Here's what we know so far.

Who is Peng Shuai?

Peng, 35, is a prominent figure in Chinese tennis with almost $10m in career prize money. Introduced to the sport by her uncle when she was eight-years-old, Peng made her WTA debut in 2001 and has since gone on to win 25 titles in singles and doubles.

She has won two women's doubles Grand Slams at Wimbledon in 2013 and the 2014 French Open, both alongside Taiwan's Hsieh Su-wei.

In 2014, she became the first Chinese player to become the world number one in doubles.

Peng has a strong social media presence, with half a million followers on Weibo, the Chinese equivalent of Twitter.

What did she say?

In a 1,600 word post on Weibo earlier this month, Peng said former Vice Premier, Zhang Gaoli, had "forced" her to have sexual relations with him.

It is the first time such an allegation has been made against one of China's senior political leaders. Mr Zhang has not responded to her claims.

"I know that someone of your eminence, Vice Premier Zhang Gaoli, you'll say that you're not afraid", Ms Peng wrote in her post, "but even if it's just striking a stone with a pebble, or a moth attacking a flame and courting self destruction, I will tell the truth about you."

She said he had first coerced her after she visited his home to play tennis. "That afternoon I didn't give my consent and couldn't stop crying," she wrote. "You brought me to your house and forced me and you to have relations".

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Peng has acknowledged that she will not be able to provide proof to back up her claims.

"I have no evidence, and it has been impossible to leave any evidence… You were always afraid that I would bring something like a tape recorder, to record evidence or something… There is no audio record, no video record, only my distorted but very real experience."

Zhang has not commented on the allegations.

Who is Zhang Gaoli?

Zhang, 75, served as vice premier between 2013 and 2018 and had previously was the top party official in Tianjin.

During his time as vice premier, he presided over preparation meetings for the 2022 Beijing Winter Olympics.

He was also involved in China's Belt and Road project and visited a number of countries as part of this. He also spoke as Xi Jinping's special envoy at a UN climate conference in 2014.

Image source, Getty ImagesImage caption, Zhang attended numerous events during his time as vice-premier

Zhang also attended major events such as People's Liberation Army celebrations and was pictured in the front row of the audience alongside President Xi Jinping.

Duowei News described Zhang has having a "pragmatic style" and claimed he had "rarely been controversial since becoming an official".

Since retiring from his role, he has stayed out of the spotlight with no coverage in Chinese media or on the government's website.

Where is Peng Shuai?

After sharing her post on Weibo, the tennis player was not heard or seen publicly for several weeks. That was until last week when state media outlet CGTN published on Twitter what it claimed was an email from Peng.

In the email, which CGTN claimed was sent to WTA chief Steve Simon, she purportedly said that the allegations are "not true".

Chinese tennis star Peng Shuai has sent an email to Steve Simon, the WTA Chairman & CEO, CGTN has learned. The email reads:

— CGTN (@CGTNOfficial) November 17, 2021
The BBC is not responsible for the content of external sites.View original tweet on Twitter

Then several days later three photos of Peng were posted on a WeChat account under her name with the caption "Happy Weekend". But the authenticity of the post has been widely questioned.

She has since reportedly appeared as a guest at a tennis tournament in Beijing. Global Times editor Hu Xijin published the footage on his Twitter account.

Image source, IOC / Greg MartinImage caption, IOC President Thomas Bach spoke to Ms Peng for 30 minutes on Sunday

On Sunday, the International Olympic Committee released a statement saying it had spoken with Peng and she appeared to be safe and well.

It said that IOC President Thomas Bach spoke with the star who "thanked the IOC for its concern about her wellbeing".

"She explained that she is safe and well, living at her home in Beijing, but would like to have her privacy respected at this time".

What has the reaction been?

Last week, the UN and US called for proof of the tennis star's whereabouts.

However, the Chinese government has not commented on the allegations.

When asked about Peng last week in a briefing, foreign ministry spokesman Zhao Lijian told reporters that the matter was "not a diplomatic question" and said he was not aware of the situation.

Censors in China were quick to take action against Peng's Weibo post. Comments on her timeline were blocked and remain so. While specific search terms such as her name were temporarily blocked.

A number of major tennis players including Serena Williams, Naomi Osaka and Novak Djokovic have spoken out in support of Peng.

The WTA has remained firm throughout the incident, requesting to speak with Peng themselves.

Steve Simon has threatened to pull out the WTA's business from the country, which would have a big effect. There are 10 WTA events scheduled to take place in China next year including the Wuhan Open and WTA finals in Shenzhen.

This video can not be played

To play this video you need to enable JavaScript in your browser.Media caption, WTA chairman: We are worried about Peng's safety

In a statement on Sunday, it said recent videos of the tennis star "don't alleviate or address the WTA's concern about her wellbeing and ability to communicate without censorship or coercion".

"This video does not change our call for a full, fair and transparent investigation, without censorship, into her allegation of sexual assault, which is the issue that gave rise to our initial concern," it added.