China is investigating the head of its state assets regulator, a former top energy executive, for "serious discipline violations", the government said on Sunday in what appears to be a deepening crackdown on corruption.
A brief government announcement said Jiang Jiemin was "suspected of serious discipline violations", shorthand the government generally uses to describe graft.
The investigation was being carried out by the ruling Communist Party's anti-graft watchdog, the statement said. No other details were given.
Jiang was promoted to head of the Assets Supervision and Administration Commission (SASAC) in March, from his previous post as chairman of energy giant China National Petroleum Company (CNPC).
SASAC is a ministerial-level body run by China's cabinet, and is directly responsible for more than 100 state-owned companies.
The announcement comes after the government announced last week that four of CNPC's top executives were under investigation for alleged wrongdoing.
The investigations, which come amid an anti-corruption campaign by President Xi Jinping, were announced shortly after the close of the trial of Bo Xilai, once a rising political star who is now awaiting a verdict on charges of graft, bribery and abuse of power.
"This was very much anticipated after the government's recent string of moves," said an energy industry analyst, referring to the probe into Jiang. The analyst declined to be identified because of the sensitivity of the matter.
CNPC is the parent of Hong Kong-listed PetroChina, Asia's top oil and gas producer and the world's most valuable listed energy company after Exxon Mobil.
The four company officials under investigation are Li Hualin, a deputy general manager of CNPC; two vice-presidents of PetroChina, Ran Xinquan and Wang Yongchun, and PetroChina chief geologist Wang Daofu.
The government has not detailed the accusations against them. It was also unclear if any of the officials or Jiang have lawyers.
Jiang, 58, became general manager of CNPC in 2006 and chairman in 2011.
He rose to prominence with the support of Zhou Yongkang, who retired earlier this year from the elite Politburo Standing Committee, where he was China's domestic security chief.
On Friday, Hong Kong's South China Morning Post newspaper said China's senior leadership had agreed to open a corruption investigation into Zhou.
The government has not commented on whether Zhou, who was also an ally of the now disgraced Bo, was being investigated.