Experts have suggested bringing in third-party supervision to prevent corruption in State-owned enterprises after a senior executive of China's biggest oil company was placed under investigation for graft.

The country's top disciplinary watchdog announced on Monday that Wang Yongchun, vice-president of the China National Petroleum Corporation, is being probed for a possible "severe discipline violation" - a term that generally refers to corruption in China.

No details were given by the Central Commission for Discipline Inspection of the Communist Party of China.