SHANGHAI—An official from China's central bank voiced his skepticism toward bitcoin on his personal microblogging account, a move that comes amid uncertainty around the digital currency's future in China.

Zhang Niannian likened bitcoin exchanges to "casinos" on Chinese microblogging website Sina Weibo in a post dated Friday. Mr. Zhang asked several rhetorical questions in his posting, including "Aren't you afraid that a bitcoin platform will leave with your money?" as well as, "Do you think the court...