HONG KONG • Chinese pop star Na Ying is quitting as mentor of Sing! China, amid relevations that the television singing contest might be rigged.

In a statement issued on Weibo on Wednesday, she said she would leave the show after six seasons. The contest was known as The Voice Of China for four years, before it was renamed Sing! China last year.

Na, the only mentor to have stayed for six seasons, said: "It's time to take a break. In six seasons, I have become more and more profoundly aware that music is fair. The brutal competition system may be the magic weapon of the show, but every time I make a choice, I suffer in my heart, I am mentally and physically exhausted."

Noting that rumours had gone round about her quitting at the end of each season, she said: "This time, it's true."

In the finals of the second season of Sing! China on Sunday, Tibetan Zahi Bing Zo (Zhaxi Pingcuo), a member of Chinese singer Liu Huan's team, won. Hunan contestant Doris Guo of Team Na Ying came in second, and Singaporean Joanna Dong of Team Jay Chou, third.

The fourth mentor, Hong Kong singer Eason Chan, spilled the beans about Sing! China on his ViuTV talk show this month, said Apple Daily.

He said there was a contestant who sang well during an audition, but not well enough for him to push a button and choose her. A director told Chan and Na to push their buttons anyway, but the two did not listen, Chan said.

On Wednesday, Hong Tao, director of another singing contest called The Singer, "liked" Na's announcement on Weibo, prompting speculation that he had invited her to join his show as a contestant.

But he later explained that his hand had slipped, and said he could swear he had not made her an offer.