BEIJING China is auditing the State Grid Corp of China, the utility said in the wake of a magazine report that one of the most senior executives in the world's largest utility was under investigation.
Caixin, a respected Chinese business magazine, reported this week that Zhu Changlin, head of the State Grid's North China operations, was under investigation, leading industry and government sources to believe State Grid could be next in line in the government's campaign against graft.
It was unclear if the investigation of Zhu, which could not be independently verified by Reuters, was related to the audit.
In a statement via its microblog on Thursday, the State Grid called the audit "routine".
"This economic accountability audit is a routine audit arranged according to our systems," it said without giving further details.
The statement added that State Grid was one of 14 major state-owned enterprises, including seven energy-related companies, being audited.
Industry sources told Reuters that State Grid Corp. - which transmits and distributes power to 1.1 billion people across nearly 90 percent of China - was the central target of this round of audits.
The goal of the audits into State Grid and other firms is unclear, but industry officials said it was unlikely that auditors would emerge empty-handed.
"They will definitely uncover a bunch of problems, big or small, from an audit of any big state-owned enterprises," said a senior Chinese power industry official.
The audit, which started last month, has sparked investor concerns that the government may consider breaking up State Grid's monopoly.
Shares of State Grid subsidiaries that produce power equipment, including Henan Pinggao Electric Co Ltd and XJ Electric, have fallen sharply in the past month. The subsidiaries rely on State Grid's spending on ultra high-voltage power transmission projects to bring in revenue.
Investors are also worried about an investigation into State Grid Chairman Liu Zhenya, a strong proponent of the controversial ultra high-voltage technology.
Liu says the technology would revolutionize long-distance power transmission and help resolve China's geographical energy imbalance, but critics say the technology is costly and untested, and could make the system vulnerable to black-outs.
President Xi Jinping has vowed to target powerful "tigers" as well as lowly "flies" in a fight against corruption that he has said threatens the Communist Party's very existence.
On Friday, the government announced that Wei Jian, a senior official with the party's graft-fighting Central Commission for Discipline Inspection, was himself being investigated for serious violation of discipline and law, the usual wording use for a corruption investigation. It gave no details.
PetroChina, and its parent firm, China National Petroleum Corp (CNPC) are at the centre of one of the biggest corruption investigations into the Chinese state sector in years.
In March, the chairman and the president of Three Gorges Corp., the company that built the $59 billion project for the world's biggest hydro-power scheme, stepped down, but they have not been accused of any wrongdoing.
The party's anti-graft watchdog published a scathing report in February saying some Three Gorges' officials were guilty of nepotism, shady property deals and dodgy bidding procedures. The dam was funded by a special levy paid by all citizens.
But analysts say a central purpose of the anti-corruption campaign may be to consolidate Xi's power and remove opposition.
"It is a way to strengthen control," said Johnny Lau, a Hong Kong-based political analyst. "We cannot expect that Xi Jinping will take action against corruption only because he wants to make things clean. There is a hidden agenda."
(Additional reporting by Li Hui and Ben Blanchard, and by Charlie Zhu in HONG KONG; Editing by Simon Cameron-Moore and Robert Birsel)