BEIJING (REUTERS) - Mr Wang Yongchun, vice-president of China's biggest oil company, the China National Petroleum Corporation (CNPC), has been put under formal investigation for "severe breaches of discipline", the government said on Monday.

China's Ministry of Supervision made the announcement in a notice posted on its official website (www.mos.gov.cn). It did not specify the alleged breaches.

Neither Mr Wang nor a company spokesman could be immediately reached for comment.

CNPC is the parent of PetroChina , China's largest oil and gas producer.

Mr Wang also serves as the head of China's largest oilfield at Daqing in the northeast.

Mr Wang had been regarded as a potential candidate to replace CNPC's former chairman, Jiang Jiemin, who was appointed as chairman of the State-Owned Assets Supervision and Administration Commission (SASAC) earlier this year. The job went to Mr Zhou Jiping in April.