Ten senior executives from energy giant China National Petroleum Corp (CNPC) have been put under investigation so far this year, and the investigation might involve some existing court cases, according to media reports on Sunday.

Two former senior executives of the Dushanzi Petrochemical Branch of CNPC, located in Northwest China's Xinjiang Uyghur Autonomous Region, are suspected of serious violation of discipline and laws, and they are placed under inspection, according to statements released by the Heilongjiang Discipline Inspection Committee late Saturday.

The two former senior executives, named Fu Dexin and Zhang Pengjiang, both started their careers in Xinjiang and worked in the Dushanzi branch for many years as senior executives. Fu retired in 2014 and Zhang retired in 2015, said the statements.

Together with other two senior executives who were under investigation earlier, there are now four people whose work backgrounds are related to the same branch of CNPC, reported by thepaper.cn.

Hu Yongqing, deputy department manager at CNPC, was said to be under inspection in February, and Ma Wenjun, department director in the Guangdong Petrochemical Branch of CNPC, also become the subject of an inspection shortly after Hu, in March.

In 2018, the Party committee of the State-owned Assets Supervision and Administration Commission of the State Council conducted two rounds of inspections of 12 SOEs, identified 356 problems and handed over 404 offenses to judicial departments, according to the People's Daily in January.