Investigators took 59 year-old Yang Jinshan, a Lieutenant General leading the Chengdu military area command, to Beijing last week as part of a corruption investigation.
His family members and secretary were also detained.
Chengdu Command overseas People's Liberation Army (PLA) operations on the Indian front in Tibet.
Yang was apparently being probed for his alleged links to disgraced Communist Party of China leader Bo Xilai, who is serving life sentence for corruption and various other charges of indiscipline, Hong-Kong based South China Morning Post reported.
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Xu, who was the military's second-highest career serviceman until he retired last year, has been accused of accepting bribes.
He was expelled from the Communist Party last month.
Several high-level PLA officials who were influential in the previous dispensation headed by former President Hu Jintao were held for corruption after President Xi Jinping took over last year.
The scrutiny of the PLA comes as Xi, who chairs the Central Military Commission, moves ahead with an overhaul of the army's leadership in an attempt to root out corruption.
Analysts say Xi is trying to put in place top officers who are loyal to him.