China is investigating the top executive of one of the country's biggest automakers FAW, the Communist Party's corruption watchdog said, as a prolonged graft crackdown targets more state-owned companies.

The chairman and party secretary of China FAW Group, Xu Jianyi, had been placed under investigation for "severe" violations of discipline and the law, the Central Commission for Discipline Inspection (CCDI) said Sunday, using a phrase that typically refers to corruption. It gave no further details.

FAW, originally known as First Automotive Works, is China's third biggest automaker with sales of more than three million vehicles last year, according to an industry group.

Headquartered in the northeastern city of Changchun, FAW and Germany's Volkswagen have a passenger car joint venture that produces the Audi brand, among others.

Volkswagen said it was aware of the matter but declined specific comment on the investigation as it was continuing. FAW could not be reached.

Besides a long career in the auto industry, Xu, now 61, also held government and party posts in Jilin province where FAW Group is based, according to his biography on the company's website.

"As a responsible corporate citizen in today's global economy, we are proud of our success in contributing to the success and prosperity of society worldwide," Xu said in an introduction to FAW on the website.

The group's Shenzhen-listed unit, FAW Car Co., closed down 1.92 percent on Monday after news of the corruption probe.

Chinese President Xi Jinping launched a much-publicised drive against corruption after he came to power two years ago, vowing to target both high-level "tigers" and low-ranking "flies".

The CCDI said early this year that it plans to investigate all major state-owned enterprises.

But analysts say China has failed to implement institutional safeguards against corruption, such as an independent judiciary and free media, leaving anti-graft campaigns subject to political influence.