The anti-corruption watchdog of China's ruling Communist Party said on Friday it would send investigators to the country's parliament for the first time ever, in a demonstration of the party's dominance over the organs of state.

All of China's governing structures, ranging from the legislature to the government and the military, are controlled by the party.

But it is the first time that the party's Central Commission for Discipline Inspection (CCDI) will send "resident supervisors" to the National People's Congress (NPC), said Chen Wenqing, a deputy head of the anti-corruption body, in a statement posted on its website.

The NPC is a rubber-stamp parliament that is proclaimed to be the "highest organ of state power" in China's constitution.

Supervisors will also be stationed in six other key agencies, including secretive party organs such as the General Office of its Central Committee, the Organisation Department -- which is in charge of performance assessment and promotion of officials -- and the Propaganda Department, in another unprecedented move in China's much-publicised crackdown on graft.

"Central and national apparatuses are hubs of the governing system of the party and the state. They have concentrated power and their status is crucial," Chen said in the statement.

"Some corruption cases uncovered in recent years have caused a vile impact on society and therefore it is very necessary and urgent to strengthen supervision" over the agencies, he said.

Setting up CCDI resident offices in the seven organisations is intended to "concretely intensify supervision over leaders and members of the relevant departments", he added.

The "supervisors" will focus on investigating the potential wrongdoings of senior officials, and will have access to the agencies' accounts and officials' reports on their personal and family finances and activities, the official Xinhua news agency said Friday.

The party's anti-corruption drive began after Xi Jinping took the helm of the organisation two years ago, with the powerful former security chief Zhou Yongkang being the highest-ranking official ensnared.

The campaign has netted high-level "tigers" as well as low-level "flies", but critics say the party has failed to introduce systemic reforms to prevent corruption, such as public disclosure of assets.