The man that police claimed died in custody while playing hide-and-seek was the victim of a vicious assault by another prisoner, prosecutors said on Friday.

"Li Qiaoming was beaten to death by prison bullies while they pretended to play a game," Yang Jianping, spokesperson for the Yunnan Procuratorate, said at a press conference.

Several prison officials and police officers on duty at the time of the man's beating have been punished or removed from their posts, Yang said.