A deputy political commissar of China's top military university has reportedly become the third major general from a military academy to be probed over the buying and selling of military ranks in the army. Major General Duan Tianjie, deputy political commissar of the People's Liberation Army National Defence University, was taken away by authorities last month, according to the news portal Caixin. Duan is the most senior political officer so far from the National Defence University to be investigated. The university, formed in 1985 with the merger of parts of the PLA Military Academy, the PLA Political Academy, and the PLA Logistics Academy, is directly controlled by the Central Military Commission. The university is regarded as China's equivalent to the United States Military Academy at West Point. "Political commissars are in charge of military cadres' promotions. The reason for investigating Duan most likely concerns the selling of ranks," a Beijing-based retired senior colonel said. "Xu Caihou asked for 6 million yuan [HK$7.6 million] for a commander of a key military region, while a regimental commander needed 1 million yuan." Xu, 71, a former vice-chairman of the CMC, was the most senior military figure implicated in President Xi Jinping's anti-graft drive launched after he took control of the Communist Party and military in 2012. The army newspaper PLA Daily last week named and shamed 16 senior military officials, half of them former political commissars with prominent academy backgrounds. They included Major General Dai Weimin , former dean of the PLA's Nanjing Political College, and Ma Xiangdong, a senior colonel and director of the military school's political department. The paper said that Gao Xiaoyan, deputy commissar of the PLA Information Engineering University in Zhengzhou, Henan was also to be investigated for taking bribes.