China's defense 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.
Zhang also sits on the party's top decision-making body, the 24-person Politburo.
His father was one of the founding generals of the Chinese Communist Party.
Zhang joined the army in 1968 and is one of the few senior leaders with combat experience.
He was kept in office beyond the customary retirement age for China's military, suggesting President Xi's confidence in him until now.
The announcement comes days after rumors appeared that Zhang and Liu could be facing an investigation as they were not present at a high-level party event in December.
Since coming to power, President Xi has launched waves of anti-corruption drives through various departments, with the military being a recent focus. He has called corruption the biggest threat to the Communist Party and acknowledged that the fight against it remains grave and complex.
Advocates of the policy argue that it promotes good governance, while critics assert it serves as a mechanism for eliminating political rivals.
With the probe into Zhang and Liu, the CMC is now left with just two members: Xi, who is the chairman, and Zhang Shengmin, who oversees the military's disciplinary affairs.
