Leadership of China's top three oil companies is in the hands of three new executives.

Wang Yupu, 59, deputy head of the Chinese Academy of Engineering, has replaced Fu Chengyu, becoming the new chairman of Sinopec Group, the Organization Department of the Central Committee of the Communist Party said on Monday.

Fu, aged 64, will retire having already served around an extra year in the job.

Most chiefs of State-owned enterprises step down at 63. Fu, who had led Sinopec since 2011, was allowed to continue beyond the designated age in July last year.

During the mid-year performance meeting in August he told shareholders that the central government decided to let him continue as chairman without a detailed timetable.

His retirement came as a surprise to industry insiders.

China's anti-graft watchdog announced last week that Wang Tianpu, president of Sinopec was under investigation for suspected "serious disciplinary violations".

Before that, Sinopec had not appeared to be involved in corruption probes compared with China National Petroleum Corp (CNPC), whose top senior officials have been taken away for anti-corruption investigations since 2013.

Central government has also announced that Wang Yilin, former CNPC executive and current chairman of China National Offshore Oil Corp (CNOOC) will become the new head of CNPC.

Wang will replace Zhou Jiping, 63, who will retire having filled the role of CNPC chairman since 2013.

Wang, born in 1956, entered the nation's oil industry with CNPC and stepped up to deputy general manager from being head of the company's subsidiary in Xinjiang Uygur autonomous region in 2003.

During the last round of leadership reshuffles of the three oil giants four years ago, he was appointed chairman of CNOOC.

After Wang returns to CNPC as new chief, his role will be taken by Yang Hua, current president of CNOOC.

Yang, born in 1961, joined the company in 1982 and began his career in CNOOC as a geologist for upstream oil exploration.

As chief financial officer of the company, Yang played a crucial role during CNOOC's largest overseas acquisition of Nexen Inc in 2013.