China has dropped one of its espionage chiefs from a high-profile panel of advisers, official news agency Xinhua said on Wednesday, after the ruling Communist Party announced he was being investigated for corruption.

Ma Jian, a vice minister at the Ministry of State Security, is the most senior security official facing investigation since former domestic security tsar Zhou Yongkang was ensnared in a graft scandal last July.

The investigation into Ma could lead to a shake-up in the powerful state security ministry, a KGB-like operation that spies on citizens and foreigners at home and abroad.

One of China’s most opaque bodies, it has no public website or spokesman.

The advisory panel, the Chinese People’s Political Consultative Conference (CPPCC) has revoked Ma’s membership eligibility, Xinhua said on its microblog, without giving details.

Last month, the party’s anti-graft watchdog said it was investigating Ma, signaling that the strongest corruption crackdown in decades has engulfed the powerful intelligence network.

It is unclear what triggered the investigation of Ma, who is said to have headed China’s counter-espionage programs.

He has since been replaced by Qiu Jin, a vice minister of state security.

Ma worked at the intelligence agency for more than 30 years, and was promoted to a deputy minister of counter-intelligence operations in 2006.

President Xi Jinping has vowed to target high-ranking “tigers” as well as lowly “flies” in his anti-corruption drive, and has pledged to step up the effort.

Story compiled with information from Reuters