Yao Gang, vice chairman of the China Securities Regulatory Commission, speaks to reporters on the sidelines of the National People's Congress in Beijing in this March 7, 2014. [Photo/IC]

A senior official at China's securities watchdog is being investigated by the country's top anti-graft body, signaling the widened government crackdown on corruption in the financial industry.

Yao Gang, vice-chairman of the China Securities Regulatory Commission, is under investigation for "serious violations of discipline", the Central Commission for Discipline Inspection of the Communist Party of China announced in a statement on its website on Friday evening.

Yao, 53, is by far the highest-ranked securities official under investigation as Beijing extends its anti-corruption campaign into the financial industry.

The investigation into Yao came after President Xi Jinping urged effective regulation of the stock market and better protection of investors' interests.

Yao's case also follows the government investigation into Zhang Yujun, former assistant chairman of the CSRC, in September.

Yao and Zhang were the major officials behind the government's latest effort to stem the dramatic market rout during the summer that wiped out $5 trillion in market value.

Yao joined the CSRC in 1993 and was promoted to his current position in 2008.