BEIJING  The top official of China’s civilian and military nuclear power programs is being investigated for “grave violations of discipline,” a phrase often used in corruption inquiries, the Chinese Communist Party’s disciplinary committee has announced.

The official, Kang Rixin, is the general manager and Communist Party secretary of China National Nuclear Corporation, a vast holding company that is spearheading plans to increase the nation’s capacity to generate nuclear power at least sixfold in the next decade.

Mr. Kang, 56, also is a member of the Communist Party Central Committee, the party’s senior ruling body, and sits on the same party disciplinary committee that is investigating him.

The announcement, issued late Wednesday, gave no indication of the accusations against Mr. Kang. The Beijing-based business journal Caijing and China Business News Daily quoted unidentified sources as saying the inquiry centered on about $263 million in company funds that apparently were invested and lost in the stock market.