A Sinopec logo is seen on top of a logo of Easy Joy store at a gas station in Beijing, September 16, 2011. [Photo / Agencies]

China's corruption watchdog has launched a series of inspections into state-owned enterprises and government bodies including China Petrochemical Corp (Sinopec Group), Asia's largest oil refiner, media said on Monday.

The inspectors, part of China's Central Commission for Discipline Inspection (CCDI), will focus on senior figures within Sinopec who may be promoted to leadership roles.

The official Xinhua news agency said the inspection would be complete within one month.

Sinopec Group is the parent company of China Petroleum & Chemical Corp. The inspection will also take in government institutions and other state companies, including China Southern Airlines Co Ltd and China Unicom (Hong Kong) Ltd.

A spokesman for China Unicom declined to comment. Sinopec and China Southern were not immediately reachable for comment.

President Xi Jinping has launched a sweeping crackdown on corruption since taking power, warning that the problem is a threat to the Communist Party's very survival and vowing to go after powerful "tigers" as well as lowly "flies".

The crackdown has so far netted Zhou Yongkang, former security chief and previously an oil industry man, and Jiang Jiemin, former head of top energy group China National Petroleum Corp, the parent of PetroChina Co Ltd.

Earlier this month, China's top prosecutor said a senior official of China National Offshore Oil Company (CNOOC) was under investigation suspected of having received bribes, the first executive from the offshore oil and gas firm embroiled by Beijing's war on graft.