The anonymous officials said they did not know specific dates or reasons associated with Wang's case.

The last public appearance by Wang was from Sept 15 to 18, when he toured the company's Xinjiang oilfields, urging local units to "spare no efforts to promote the anti-corruption drive".

Han Xiaoping, chief information officer of China Energy Net Consulting Co Ltd, said the anti-corruption drive will help boost China's oil industry reform.

"The monopoly in the oil industry has stood in the way of technology upgrading and business growth for a long time," he said. "Market-oriented reform is the right path for CNPC's development."

The National Development and Reform Commission, the country's economic planner, is also in the spotlight of the anti-corruption campaign.

Among the most recent NDRC officials detained on suspicion of corruption, five were from the commission's pricing department, which is in charge of policy for the energy industry.

Corruption in media needs to be stamped out with decisive steps	CNPC aims to curb embezzlement in subsidiaries