OREANDA-NEWS. September 25, 2013. A corruption investigation into PetroChina has put the spotlight on Chinese entrepreneur Hua Bangsong and the links that his company, Wison Engineering Services, has with the oil giant.

The founder and chairman of Wison was helping Chinese authorities with an unspecified investigation, Wison said on Sept. 3 amid a widening probe into PetroChina and its parent China National Petroleum Corp (CNPC).

Shares in Shanghai-based Wison - which has gotten most of its revenue from PetroChina in recent years - have been suspended in Hong Kong since then. They had fallen 30 percent after the Chinese government announced the investigation into several former top executives at PetroChina and CNPC in late August.

In a statement on Friday, Wison said Hua "is still assisting relevant authorities" but that it had not been informed about the nature of the investigation. It said Wison was considering appointing an acting chairman.

Wison was operating normally and would continue to service its existing contracts, it added.

"The company has relied excessively on one customer - PetroChina - so naturally the news about the chairman, the founder sparked fears about the company's future," said Wu Da, a portfolio manager at Beijing-based Changsheng Fund Management Co Ltd, which does not own shares in Wison but has shares in its larger rival Sinopec Engineering.

Hua, 47, could not be reached for comment. A Wison spokeswoman turned down a Reuters request for an interview with him, saying it was "inconvenient" for Hua.

According to Wison's filings with the Hong Kong stock exchange, Hua founded the company in 1997 and built it into China's largest private petrochemical contractor thanks largely to revenue from PetroChina, one of the world's most valuable energy firms with a market capitalisation of about USD240 billion.

Since 2002, Wison has won numerous engineering, procurement and construction (EPC) contracts for PetroChina's petrochemical and refining projects in a sector dominated by state-owned contractors, including units of PetroChina and Sinopec Group, parent of Sinopec Corp , Asia's largest refiner.

Between 2009 and 2011 for example, Wison booked 8.1 billion yuan (USD 1.32 billion) in revenue from PetroChina, according to filings, accounting for the majority of its revenue over that period.

Wison said it won the contracts because of its technical capabilities, experienced team and track record. Many of its senior staff are Chinese oil industry veterans, some of whom used to work for PetroChina, according to its website.

Wison ranked fifth in terms of EPC revenue from China's oil refining and chemical industries in 2011 and 2010, according to the share offer prospectus of Sinopec Engineering.

It was the only privately controlled firm among China's top 10 refining and chemical EPC contractors - a group that held 47.2 percent of the market in 2011 with total combined revenue of 129.5 billion yuan.