Ma Xingrui, who is also a former Communist Party boss of Xinjiang, is the third member of the Politburo -- an elite party body comprising around 20 of the country's top leaders -- to be investigated since its term began in 2022.

Ma is suspected of "serious discipline and law violations" -- a phrase used in China to refer to corruption -- and is currently under investigation by the party's Central Commission for Discipline Inspection, state broadcaster CCTV reported.

Ma ran the western Xinjiang region, where rights groups have alleged abuses against Muslim minorities, from 2021 until he was removed in July last year.

Ma, who joined the Politburo in 2022 at the 20th Communist Party Congress, is the latest member of the body to fall to Xi's efforts that have focused on the military in recent years, with several top generals removed.

Ma's downfall comes after Zhang Youxia, a vice-chairman of the Central Military Commission (CMC) -- China's top military body headed by Xi -- and also a member of the Politburo, was placed under investigation in January.

He Weidong, also a vice-chairman of the CMC and Politburo member, was expelled from the Communist Party and removed from his positions in October 2025 following a corruption probe.

Those removals left just two members -- discipline head Zhang Shengmin and Xi himself -- on the CMC, down from the original seven in 2022.