BEIJING—China has placed under investigation the head of its national energy-planning agency—and the most prominent ethnic Uighur in the government—as part of a campaign against graft and other official misdeeds.

Nur Bekri, who is also deputy chief of the national economic-planning agency, is being probed for “serious violations of discipline and law,” the Communist Party’s Central Commission for Discipline Inspection said in a brief statement Friday. The allegation is usually used to describe corruption cases.

Mr....