Investigations into a former senior official in East China's Zhejiang province have sent a clear message that nobody is off-limits in China's anti-corruption drive, the People's Daily said on its WeChat account.

In only seven regions have officials above provincial level so far evaded the top graft buster's microscope.

They are the Beijing and Shanghai municipalities, Jilin and Fujian provinces and the Tibet, Ningxia Hui and Xinjiang autonomous regions.

Si Xinliang, former vice chairman of the Zhejiang provincial committee of the Chinese People's Political Consultative Conference, is under investigation for "suspected serious discipline and law violations", the Central Commission for Discipline Inspection (CCDI) said on Monday.

The phrase "suspected serious discipline and law violations" is Chinese shorthand for infringements including corruption.

Si is the first "big tiger" snared in Zhejiang and the fourth ministry-level official to be probed since the 18th National Congress of the Communist Party of China.

Zhejiang is a special place in China's political landscape as many senior Party and government leaders once worked there. Chinese President Xi Jinping served as Party secretary of Zhejiang province between 2002 and 2007.

Xi said at a meeting in June last year that the places where senior Party and government leaders once worked would be treated no differently when the CCDI chooses targets for inspection.

The investigation of Si came months after the discipline watchdog sent an inspection team to Zhejiang and found discrepancies.

Xi last month urged disciplinary officials to take a zero-tolerance stance on corruption, saying "strong remedies must be continuously used to cure the illness."