Former Chinese security chief Zhou Yongkang has been sentenced to life in prison after a secret trial, making him the highest-level official convicted in President Xi Jinping’s signature campaign against corruption.

The former member of the Communist Party’s supreme Politburo Standing Committee pleaded guilty to charges of bribery, leaking state secrets and abuse of power, the official Xinhua News Agency said in a social media posting Thursday.

He will not appeal the charges, Xinhua said.

Zhou’s position on the Standing Committee from 2007 to 2012 would have given him the highest level of access to information on the party and the government. Zhou is the biggest "tiger" snared in the corruption clampdown led by Xi, who pledged to pursue abuse by both "tigers and flies" within the party after taking power at the end of 2012.

In a editorial after the investigation was announced in July, Xinhua News Agency said it ended "a myth among many people that senior leaders are regarded to be immune from the party discipline regulation and the country’s law enforcement."

After Zhou retired from the Standing Committee, investigators began to probe several people in his circle, including his son Zhou Bin, executives at his former employer China National Petroleum Corp., and officials in Sichuan province where he was party secretary.

The People’s Daily in November called the investigations into people around Zhou the five "peripheral wars" against the groups with links to him.

The charges against Zhou were filed in April in the No. 1 Intermediate People’s Court in Tianjin, a city about 120 kilometers (about 75 miles) southeast of Beijing. Prosecutors called his alleged crimes "particularly serious."