Image copyright Getty Images Image caption Peng Shuai was training in Qatar at the time of her disappearance
Peng Shuai has been missing since she was due to compete at the WTA finals in Singapore on 16 November.
The WTA tournament’s executive chairman David Brewer said Peng “is still missing”, and the pair have not heard from each other since.
MissingPlayer Report, an initiative by retired tennis players from 14 countries, is now calling for a boycott of the tournament as Peng’s team is “not credible”.
President of the Women’s Tennis Association Katrina Adams said the organisation is “reaching out” to Peng’s team.
“We are taking it very seriously, and the player is well-liked in the sport,” she said.
Frenchwoman Kristina Mladenovic tweeted: “It’s absolutely unacceptable that a player who put herself in that position, voluntarily and willingly, had to be in the position she is in. We need clarity.”
Peng, 29, won the WTA Finals in 2017 to become the first Chinese player to reach a WTA singles final.
She reached the semi-finals of the women’s singles this year.
Speaking at the Madrid Open earlier this month, she said: “So many things I want to do, but I don’t know if I can do them.”
Senator Bernie Sanders, from US presidential hopeful’s Bernie Sanders 2020, tweeted his support of missing player’s efforts.
Barack Obama’s grandson, Jordan, also made a statement saying that “young people all over the world” should protest the “total lack of transparency by the WTA, particularly concerning the whereabouts of Peng Shuai”.
Theresa May and Jeremy Corbyn have both issued statements on the case.
May told MPs: “It is shocking that Peng Shuai is missing – and all that is known about her whereabouts is that her team have not been able to contact her in months.”