The United States is “deeply concerned” about the controversy surrounding the disappearance of Chinese tennis professional Peng Shuai, who has gone missing after accusing a former top Communist Party official of sexually assaulting her, the White House said on Friday.

White House Press Secretary Jen Psaki said President Joe Biden’s administration wants China to “provide independent, verifiable proof” of her whereabouts, according to AFP inputs.

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The US contact came as international concerns for the tennis star has mounted since she went missing earlier this month after saying that she was sexually exploited by a former Chinese vice-premier.

On Friday, the United Nations demanded a complete inquiry into the allegations made by Peng, the former world number one doubles player, against Communist Party grandee Zhang Gaoli.

Peng wrote in a lengthy social media post on November 2 that she was forced to have sex three years ago with Zhang in his home despite repeated refusals. Zhang, 75, is a former vice-premier who was a member of the ruling Communist Party’s all-powerful Politburo Standing Committee.

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Tennis players, sports organisations, governments, and human rights activists have all come out in support of Peng, 35, and have sought answers. The 35-year-old former top-ranked player in women’s doubles won titles at Wimbledon in 2013 and the French Open in 2014. Peng also participated in three Olympics, making her disappearance all the more prominent with Beijing set to host the Winter Games starting February 4.

If Peng continues unaccounted for and her sexual assault charges are not investigated, the chairman of the Women’s Tennis Association (WTA) has stated that he is willing to break lucrative economic connections with China.

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Serena Williams, Novak Djokovic and Naomi Osaka have also voiced their concerns for one of China’s greatest ever players.

Meanwhile, China’s Foreign Ministry yet again insisted on Friday that it wasn’t aware of Peng’s disappearance.