Chinese enterprises are now the target of an anti-corruption drive launched by China's new leadership which would like to be seen as being tough on corruption.
The government has recently been investigating government officials and foreign multinational companies suspected of corruption. Among those being probed is GlaxoSmithKline.
The crackdown on local enterprises include PetroChina Co., the nation’s most valuable company, which has ousted three executives amid the probe.
The PetroChina executives to resign are Li Hualin, chairman of Kunlun, an oil and gas producer and distributor; PetroChina vice president and general manager of its biggest oilfield, Ran Xinquan; and Wang Daofu, chief geologist for PetroChina.
The senior officials have been put under investigation for "severe breaches of discipline," said the State-Owned Assets Supervision and Administration Commission (SASAC).
A PetroChina spokesman said the company "does not tolerate any official involved in corruption or other crimes," but said the investigation would not affect the company's operations.
The investigation on PetroChina was announced shortly after the close of the trial of Bo Xilai, a politician awaiting a verdict on charges of corruption, bribery and abuse of power.
PetroChina fell to HK$8.27 at the close in Hong Kong. Kunlun plunged to HK$10.88, compared with a 1.6 percent drop in the benchmark Hang Seng Index.