Chinese tennis star Peng Shuai, whose whereabouts have been a matter of international concern for weeks, attended a tennis tournament in Beijing on Sunday, according to official photos published by the tournament organised by China Open.

Peng can be seen among guests at the Fila Kids Junior Tennis Challenger Finals, dressed in a dark blue jacket and white trousers, according to the pictures published on the event's official WeChat page.

The former doubles world No.1 had not been seen or heard from publicly since she said on Chinese social media on November 2 that former vice premier Zhang Gaoli had coerced her into sex and they later had an on-off consensual relationship.

Neither Zhang nor the Chinese government have commented on her allegation. Peng's social media post was quickly deleted and the topic has been blocked from discussion on China's heavily censored internet.

World tennis bodies have expressed concern, with the Women's Tennis Association (WTA) threatening to pull tournaments out of China.

The United States and Britain have called for evidence of Peng's whereabouts and safety.

The photographs and video footage of Peng that emerged on Sunday remain "insufficient" and do not address the WTA's concerns, a spokesperson for the group told Reuters by email.

The US and British embassies in Beijing did not immediately respond to Reuters requests for comment on her reappearance.

The issue of Peng's safety and whereabouts has emerged as China prepares to host the Winter Olympics in Beijing in February amid calls from global rights groups and others for a boycott over its human rights record.

A photo of Peng at the Fila tournament was also posted on Twitter by Ding Li, a senior executive of Global D-Sports, a company which corporate information app Tianyancha says organises sport events and manages athletes.

Ding, who told Reuters he was a long-time friend of Peng's, said her phone is always switched on, so the WTA could just call her.

WTA Chairman and chief executive Steve Simon, however, told Time magazine last week that the organisation had tried to contact her through various means.

Ding said Peng was not accepting foreign media interviews as she received many calls after Simon had sent an email to her assistant that contained her contact information, and copied a number of people in his message.

The WTA did not immediately respond to a request for comment on that email. Twitter is blocked in China.

On Saturday night, Peng visited a popular restaurant in downtown Beijing for a meal Ding attended, according to photos he posted on Twitter.

Hu Xijin, editor-in-chief of the state-backed Global Times reposted a video of the outing, which a restaurant manager confirmed to Reuters on Sunday.

Seven people including Peng were at the Sichuanese restaurant, said the manager, Zhou Hongmei, adding that they ate in a private room and were joined by the restaurant's owner.

"It was crowded at the restaurant as usual," Zhou said, showing a bill that included noodles and bamboo shoots. "They didn't have much. I think they mostly chatted."

Searches on Chinese platforms for social media posts on Peng's allegations continued to yield no results on Sunday.

On some video-sharing websites like Bilibili, Peng's name was also not found in searches.

Some old videos featuring Peng could still be found, but access to their comments sections was locked.