Wison Engineering Services Co Ltd, China's oil construction company, announced its controlling shareholder Hua Bangsong was assisting 'relevant authorities' in China. The authorities were conducting an inquiry as to the Wison's share price falls,

Amongst the major clients of Wison is PetroChina and it did not provide any comment on the ongoing investigation. It did issue a statement after Chinese media reported as to the business relationships the firm had with PetroChina. The statement read, "The group's revenue recognized from contracts with PetroChina and its subsidiaries for the six months ended June 30, 2013 was insignificant."

Hua, for his part, was not immediately available for comment.

Last Sunday, Beijing announced an investigation was being conducted on the head of its state assets regulator, who also held the position of chairman for PetroChina. The said investigation was for 'serious discipline violations' in what is deemed as a deepening crackdown on graft and corruption as the Chinese Communiist Party moves for more reform in its governance.