China's ruling Communist Party says it has launched an investigation against the head of state-owned China Telecom, as Beijing expands its anti-corruption campaign to more state sectors.

The party's disciplinary arm, the Central Commission for Discipline Inspection, said on its website Sunday that Chang Xiaobing, chair of the powerful telecommunications company, has been placed under investigation on suspicion of having "severely violated disciplines."

It did not detail possible infractions by Chang, but the phrase typically means corruption. Chang formally was the chairman of China Unicom, another major state-owned telecommunications company.

Chinese President Xi Jinping launched the anti-graft campaign after he took office in early 2013. The drive has since expanded, with Xi warning that prevalent corruption threatens the party's rule.