The announcement marks the latest push in a sweeping drive to root out graft at all levels of the party and state since President Xi Jinping came to power more than a decade ago.

"Following a review... it has been decided to initiate an investigation into Zhang Youxia and Liu Zhenli," the defence ministry said in a statement.

The two men were "suspected of serious violations of discipline and the law", the ministry said.

Zhang Youxia, 75, is the more senior general of two CMC vice chairmen.

He shares the title with Zhang Shengmin, a general in Beijing's secretive rocket force and who is no relation.

Zhang Shengmin was promoted to the post in October after Beijing expelled his predecessor in another sweeping corruption purge.

Both generals rank below Xi, who has held the CMC chairmanship since 2012.

Liu, 61, is the chief of staff of the CMC's joint staff department.