China's defence ministry says it has opened an investigation into the country's highest-ranking general over "grave violations of discipline and the law".
The ministry gave no further details about accusations against General Zhang Youxia, who has widely been seen as President Xi Jinping's closest military ally. However in China the accusation of wrongdoing is usually a euphemism for corruption.
In its announcement, the ministry said another senior military officer, General Liu Zhenli, was also under investigation.
Their removal follows the expulsion of nine top generals in October - one of the largest public crackdowns on the military in decades.
Zhang, 75, is a vice-chairman of the Central Military Commission (CMC) - the Communist Party group headed by President Xi which controls the armed forces.
