HONG KONG (AP) -- Chinese authorities investigating corruption at the country's state-owned oil giant have seized records and frozen bank accounts at a PetroChina Co. supplier, the company said Thursday.
Wison Engineering Services Co. also said it couldn't contact its chairman, Hua Bangsong, who is one of the country's richest self-made entrepreneurs.
The Shanghai-based company, which said earlier this month that Hua was helping with the investigation, said he was "still assisting relevant authorities." The company said Zhao Hongbin, the manager of the finance department at a subsidiary, is also assisting.
"Mr. Hua is not contactable and he is not able to discharge his daily duties," Wison said. Forbes estimates Hua, who founded Wison in 1997, is worth $1.2 billion.
Analysts say the investigation appears to be part of efforts by China's new leadership under President Xi Jinping to tighten control over state-owned energy companies.
Four executives at PetroChina or parent China National Petroleum Corp. have already been detained and former CNPC chairman Jiang Jiemin has been fired as head of the Cabinet commission overseeing state-run companies.
In a statement to the Hong Kong stock exchange, Wison said regulatory authorities have inquired "about certain projects of the group, taken books and records and frozen certain bank accounts."
Wison said it hasn't been told about the nature of the investigation or details about how Hua and Zhao are involved. It added that some of the affected bank accounts were later unfrozen.
Wison said in a separate statement that its chief financial officer, Chen Wenfang, has resigned. The statement didn't make reference to the investigation and it's not clear whether his resignation is related.
Wison has been trying to downplay its relationship with PetroChina. The company said earlier this month that only 5.6 percent of its revenue in the January-June period, or 111 million yuan ($18 million), came from the oil giant. It also has four outstanding PetroChina contracts worth a total of 204.2 million yuan ($33.3 million).
PetroChina, with some 550,000 employees, is Asia's biggest oil producer by volume.
Wison Engineering: http://www.wison.com