BEIJING (Reuters) - China will prosecute for graft a former senior executive at second-largest telecom carrier China Unicom, the anti-corruption agency of the ruling Communist Party said on Wednesday.

Zhang Zhijiang, who previously headed the network construction division at Unicom, joins a long list of executives at state-run firms that have recently been caught by the party dragnet, including many at China National Petroleum Corporation, the energy giant associated with the disgraced politician Zhou Yongkang.

The party graft watchdog, the Central Commission for Discipline Inspection, said Zhang had "used his position to seek personal gain and received enormous sums of bribes". He would also be expelled from the party, it said in a brief statement.

Zhou Xiaoke, a Hong Kong-based spokesman for China Unicom, declined to comment further on Zhang's case.

Unicom sacked Zhang two weeks ago after the watchdog named him the target of a corruption probe, part of President Xi Jinping's widespread anti-corruption drive. Another Unicom executive, Zong Xinhua, was also removed from his post after being investigated for graft.

Last month, senior anti-graft officials said they would shift their attention back to China's sprawling state-owned enterprises, which have long been plagued by underperformance and corruption despite reform efforts by central leaders.

The last large-scale anti-corruption campaign to sweep through the telecom sector took place in 2011, when several China Mobile executives were caught in bribery schemes and at least one received a death sentence.