Zhang Huawei, a former division head for the top anti-corruption watchdog, is himself being investigated for suspected corruption.

The Communist Party of China Central Commission for Discipline Inspection issued a statement on its website on Monday saying that Zhang - who was a senior official at the level of vice-minister - "had seriously violated the Party's code of conduct".

According to Capitalnews, the WeChat account of Beijing Daily, Zhang is the only head of a national inspection team to be investigated.

Yang Weidong, a law professor at the Chinese Academy of Governance, said the move demonstrates the determination of the top anti-graft body to crack down on corruption, including internally.

"The move is in line with the call from the CCDI that no area is untouchable in graft investigations - the zero-tolerance stance," Yang said, adding that Zhang's case signals that there are no exceptions in the nationwide anti-graft campaign.

"More significantly, the case shows the public that anti-graft watchdogs exercise the same iron policy within their own ranks," Yang said.

Zhang took part in several rounds of inspections between 2013 and 2015, either as deputy head or head of a national-level inspection team, according to information on the CCDI website. The teams were stationed at major organizations and companies, including Renmin University of China, China Guodian Corp and the General Administration of Sport.

Wang Qishan, head of the CCDI, said in a meeting in December that 38 officials within anti-corruption bodies at the national level and more than 7,200 anti-graft officials at all levels across the country have been disciplined since late 2012.

Answering public concerns over "who watches the watchers", the CCDI has passed rules for inspectors, clarifying procedures for handling cases and disposing illegal gains.

Xinhua contributed to this story.

zhang_yi@chinadaily.com.cn