A Chinese state-run broadcaster on Thursday unveiled what it says is an email from female tennis player Peng Shuai, who claimed to have an affair with a former vice premier, but doubt grew over whether it was really written by her.

The official China Global Television Network posted a picture of the email on its Twitter account, as concern is mounting over her safety after she confessed an unhealthy relationship with Chinese veteran politician Zhang Gaoli early this month.

Peng Shuai of China is pictured at the U.S. Open in Sept. 2014 (Getty/Kyodo)

CGTN released the picture of the email, purportedly sent from Peng to Steve Simon, the head of Women's Tennis Association, saying in English, "I'm not missing, nor am I unsafe. I've just been resting at home and everything is fine."

The picture of the email also said the news, "including the allegation of sexual assault, is not true."

Simon, however, said, "The statement released today by Chinese state media concerning Peng Shuai only raises my concerns as to her safety and whereabouts. I have a hard time believing that Peng Shuai actually wrote the email we received."

"I have repeatedly tried to reach her via numerous forms of communication, to no avail," Simon added in a statement, with many famous tennis players, such as Japan's Naomi Osaka, recently expressing anxiety about her safety.

Peng has won the women's doubles at both Wimbledon and the French Open -- two of the four major tournaments in the world.

Meanwhile, Zhang served as a member of the Politburo of the ruling Communist Party's Central Committee from 2012 through 2017 under the leadership of President Xi Jinping.

In early November, a social media post spread online, which said under her name that she had sexual relations with Zhang when he was the top party official of Tianjin.

The post on Weibo, China's equivalent to Twitter, was swiftly deleted. It is unknown whether what appears to be her claim is true, although a reporter for a Chinese newspaper said it looks reliable.