The vice chairman of China’s biggest state oil producer is under investigation for “serious disciplinary violations,” becoming the latest target of the Communist Party’s massive anti-corruption crackdown.

Liao Yongyuan, vice chairman of PetroChina Ltd. and general manager of its parent company China National Petroleum Corp. (CNPC), was placed under investigation for alleged “serious violation of the law,” the party’s Central Commission for Discipline Inspection (CCDI) announced on Monday, according to BBC. A separate statement by PetroChina said that Liao was suspected of violating discipline.

PetroChina and CNPC are key targets in the anti-corruption drive that President Xi Jinping has made a central part of his rule. So far, over a dozen senior officials at the two companies have been targeted since August 2013.

CNPC said it “firmly supports” the central government’s efforts to investigate it and will “actively cooperate” with officials, Bloomberg reported.

Liao had been a 30-year veteran of the Chinese oil sector, and held significant power over the country’s industry. In the 1990s, he played a key role in oil exploration in China’s remote northwest. He was named general manager of Tarim oilfield in the northwestern Xinjiang sector in 1999, and promoted to vice chairman of PetroChina in 2005.

CNPC is among 26 state enterprises investigators are looking into for alleged graft and corruption charges. The list also includes China National Offshore Oil Corp. and State Grid Corp. of China.

On Sunday, CCDI also announced that it is looking into FAW, a state-owned enterprise that is China’s third-biggest auto manufacturer, according to local news site CCDI officials reportedly said they found FAW breaching Communist Party rules “from time to time” during inspections between July and August last year.

The anti-corruption net has also snared party luminaries such as former CNPC Chairman Jiang Jiemin and security chief Zhou Yongkang. None of the senior oil executives facing accusations have yet stood trial. About 100,000 officials have been disciplined at various levels of the national bureaucracy in the last two years.

The CCDI does not have the ability to formally arrest or press charges, but can effectively hold and investigate any of China’s 87 million party members indefinitely, Bloomberg reported.

PetroChina is Asia’s biggest oil and gas producer, but is reportedly seen by other companies as bloated and inefficient, USA Today reported. At least four former or current executives of PetroChina or CNPC are under investigation. Zhou was also formerly the general manager of CNPC.

High-ranking officials like Liao, Zhou, and Jiang, targeted by Xi’s anti-corruption drive, are considered “tigers,” while the lower level local officials are termed “flies.”