Tennis star Peng Shuai's allegations that she was sexually assaulted by a powerful Chinese politician "must be investigated fully, fairly, transparently and without censorship," the head of the WTA said Sunday.

Peng, an ex-world number one doubles player, purportedly made the claim about former vice premier Zhang Gaoli in a post on the Twitter-like Weibo earlier this month.

"The recent events in China concerning a WTA player, Peng Shuai, are of deep concern," said WTA chairman Steve Simon.

"We expect this issue to be handled properly, meaning the allegations must be investigated fully, fairly, transparently and without censorship."