The Women's Tennis Association (WTA) has demanded a "complete, fair, and transparent investigation" following sexual assault charges leveled against a former Chinese vice premier by player Peng Shuai.

In a statement on Monday, the WTA also called for an end to censorship against the former world's number one doubles player.

Peng, one of China's most prominent athletes, said on November 2 on her Weibo social media account that Zhang Gaoli pushed her into sex, and the two later had an on-again, consensual relationship.

Peng stated that she lacked evidence to substantiate her claims.

The post was removed approximately 30 minutes after it was published.

China's internet is extensively regulated, and the personal lives of senior officials are compassionate. Zhang, aged 75, served as vice premier from 2013 to 2018 and as a member of China's Politburo Standing Committee, the country's highest decision-making body, from 2012 to 2017.

Concerns have grown among the international tennis community as Peng has not been seen since the post.

The WTA stated that it would seek a "complete, fair, and transparent investigation" into the former Chinese leader's sexual assault allegations.

"The recent events in China involving a WTA player, Peng Shuai, are deeply troubling," WTA Tour Chairman and CEO Steve Simon stated in a statement.

"Peng Shuai, like all women, deserves to have their voices heard, not censored. Her allegation that a previous Chinese leader engaged in sexual assault must be taken extremely seriously."

Peng was the world's number one doubles player in 2014, becoming the first Chinese player to accomplish so after winning the Wimbledon and French Open doubles titles in 2013.

China, the Tour's most aggressive expanding market over the last decade, staged nine tournaments in 2019, including the elite WTA Finals, totaling $30.4 million in prize money.

The season-ending WTA Finals, which features the world's top eight singles players and eight doubles teams, featured a $14 million prize money in 2019 when held for the first time in Shenzhen. This year, the Finals were postponed due to the COVID-19 outbreak and relocated to Guadalajara, Mexico.

The WTA announced that the tournament will return to Shenzhen in 2022 and will remain there until 2030.

"I believe that everyone understands fully what is at stake here on a variety of fronts as we proceed," Simon told the New York Times on Sunday. "I believe we are all completely united, from players to board to council, in believing that the only acceptable approach is to do what is right."

According to Simon, no one on the WTA Tour has spoken directly to Peng but has received guarantees of her safety from the Chinese Tennis Association.

"Several sources, including the Chinese Tennis Association, have confirmed that she is safe and not in any physical danger," Simon told the Times.