China’s ex-security chief Zhou Yongkang is being investigated for suspected “serious disciplinary violation”, state media say.

The news confirms rumors about the hugely powerful former minister, who has not been seen in public for months.

Zhou Yongkang headed China’s Ministry of Public Security and was a member of the top decision-making body, the Politburo Standing Committee.

The move to target him will send shockwaves through the political elite.

Zhou Yongkang is the most senior Chinese official to be investigated since the Gang of Four – which included the wife of late leader Mao Zedong – in the early 1980s.

China’s ex-security chief Zhou Yongkang is being investigated for suspected serious disciplinary violation

He retired in late 2012, as Xi Jinping took over from Hu Jintao as the Communist Party leader and China’s president.

Since the transition, Xi Jinping has introduced a wide-ranging crackdown on corruption within the party, warning graft could threaten the organization’s very survival.

In a brief statement, state-run Xinhua news agency said the investigation would be conducted by the Communist Party’s corruption watchdog, the Central Commission for Discipline Inspection.

No timescale was given for the probe, which has been widely expected.

Several individuals believed to have had close ties to Zhou Yongkang have also been targeted in corruption investigations in recent months.

Zhou Yongkang’s career saw him head both the ministry charged with overseeing domestic security and China’s largest energy company, the China National Petroleum Corporation (CNPC).

He was also the party’s top official in Sichuan province.

Allies of his from all three areas are now the subject of various investigations.

Only a handful of people serve on the Politburo Standing Committee (in Zhou Yongkang’s time nine, currently the number is seven) and they are seen as the most powerful individuals in China.

Zhou Yongkang was also an ally of Bo Xilai, the one-time high-flying former Chongqing party chief who was jailed last year.

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