PetroChina vice chairman Liao Yongyuan is being investigated for “serious disciplinary violations”, the company said, as an anti-corruption crackdown reaches deeper into the Chinese state-owned oil giant.

In a brief statement, PetroChina said the company, China’s top oil and gas producer, was operating normally. Liao is the most senior of two vice chairmen at PetroChina, making him the company’s number two official.

Hours earlier, China’s corruption watchdog said Liao was under investigation for “serious disciplinary violations”, usually shorthand for graft, stemming from his role as a general manager of China National Petroleum Corporation (CNPC), the parent company of PetroChina. CNPC could not immediately be reached for comment. The graft watchdog, the Central Commission for Discipline Inspection (CCDI), gave no further details in a short statement.

Liao, a 30-year veteran at CNPC, was appointed vice chairman of PetroChina in May 2014, just months after China announced that several top executives from the two companies were under investigation. That included Jiang Jiemin, former chairman of both entities.

President Xi Jinping has spent the past two years waging war on corruption, saying it threatens the survival of the ruling Communist Party. Scores of senior officials in the party, the government, the military and state-owned enterprises have been brought down by the campaign. None of the detained oil executives have stood trial.

Some were proteges of former security tsar Zhou Yongkang, who was arrested last year and expelled from the party, accused of crimes ranging from taking bribes to leaking state secrets. Zhou rose through the ranks at CNPC and from 1996-1998 served as general manager of the firm. The graft watchdog said last month it had targeted 26 major state-owned firms for inspections this year, including CNPC, China National Offshore Oil Corp, and China National Nuclear Corp.