China is investigating a senior banking regulator, the anti-corruption watchdog said Tuesday, as the government steps up a crackdown on the financial sector.

Yang Jiacai, assistant chairman of the China Banking Regulatory Commission, is "suspected of a severe disciplinary violation", the Central Commission for Discipline Inspection said in a statement announcing the probe.

The phrase is often a euphemism for corruption.

Yang is the latest high-ranking official of a Chinese financial regulatory body to be placed under investigation in recent weeks.

The anti-graft commission announced last month that Xiang Junbo, the head of the China Insurance Regulatory Committee, was also being probed.

President Xi Jinping has been spearheading an unprecedented anti-corruption campaign since assuming power over four years ago, but critics say the crackdown is open to abuse for political reasons.

A court last month sentenced Ai Baojun, the ex-director of Shanghai's free-trade zone and a former vice mayor of the city, to 17 years in prison for corruption -- saying he pocketed $7.2 million through embezzlement and taking bribes.

Authorities are paying greater attention to the financial sector, particularly the vast amounts of unregulated and risky bank lending that has fuelled China's spectacular growth for years, amid fears the country is flirting with a major crisis.

New banking regulator Guo Shuqing, installed in March, issued what the official Xinhua news agency called a "regulatory windstorm" of directives last month.

They include measures to strengthen institutional transparency and chronically weak internal controls, tighten balance sheets, halt risky lending and dispose of bad loans.

Big fines have been meted out and corporate figures arrested.