China's former security chief Zhou Yongkang has been sentenced to life imprisonment for bribery, abuse of power and leaking national secrets. 

Seventy-three-year-old Zhou is the highest Communist Party member ever to face corruption charges, according to Xinhua News. 

He was tried at Intermediate People's Court in northern city of Tianjin on May 22 and was convicted of taking bribes of about $21 million and leaking of "extremely confidential" documents to an unauthorised person in a closed-door trial, Reuters reported.  

"Zhou took the advantage of his position to seek profits for five persons identified as Wu Bing, Ding Xuefeng, Wen Qingshan, Zhou Hao and Jiang Jiemin and personally accepted money and property worth 731,100 yuan from Jiang," the judgement said, according to Xinhua News.

Zhou pleaded guilty and decided not to appeal against the judgement.

"The basic facts are clear. I plead guilty and repent my wrongdoing," Zhou confessed in his final statement.

"Those involved, who bribed my family, were actually coming after the power I held, and I should take the main responsibility. I broke the law and Party rules incessantly, and the objective facts of my crimes have resulted in grave losses of the Party and the nation."

Zhou was one of China's most powerful men until his retirement three years ago, BBC News reported. He was head of Ministry of Public Security at the time and was also a member of the Communist Party of China (CPC)'s Politburo Standing Committee.

However, Zhou's secret corruption trial left many questions unanswered, according to The Guardian, which stated that the trial "exposed not only rampant corruption at the very top of the Communist party but also links between senior government officials and a mysterious fortune teller known as the 'Xinjiang sage.'"