BEIJING (REUTERS) - An investigation into China's former domestic security chief is probing five different networks, the newspaper of the ruling Communist Party said on Friday, naming senior figures it said may have benefited from his alleged corruption.

The party announced in July that Zhou Yongkang was being investigated for suspected "serious disciplinary violations", the usual euphemism for corruption, though it could also imply additional wrongdoing.

The website of the official People's Daily said the five networks included officials from Sichuan province, where Zhou was party secretary, and colleagues from his time as head of state oil giant China National Petroleum Corporation (CNPC).

Among those named were Li Chuncheng, a former deputy party boss of Sichuan; Jiang Jiemin, the former top regulator of state-owned enterprises; and former deputy police chief Li Dongsheng.

Also under scrutiny were former colleagues and secretaries from when Zhou was public security chief, and seven relatives of the accused man, including his son Zhou Bin.

Zhou is one of China's most powerful politicians of the last decade, and by far the most prominent figure caught up in President Xi Jinping's crackdown on corruption.

He is the most senior Chinese official to be ensnared in a graft scandal since the Communist Party took power in 1949.

Earlier this month, a party official was quoted as saying he had caused serious economic damage with his "meddling" in Sichuan, where he had his power base.

Zhou was last seen in public more than a year ago.

It has not been possible to contact him for comment and it is unclear if he has a lawyer.