Following former PetroChina boss Jiang Jiemin and several senior officials in the company being investigated by authorities for corruption, it is alleged that Winson Engineering Services is also involved in the scandal.

The stock price of Winson dropped by 16.46% yesterday morning before the company suspended trading of the stock.

Later Winson announced that its revenue recognized from contracts with PetroChina and its subsidiaries was insignificant and Hua Bangsong, the controlling shareholder of the company, is now assisting the relevant authorities in China in their investigations.

Winson is the largest private EPC service provider in China. Hua Bangsong controls 78.13% equity and is the largest shareholder of the company.