"There must be no hiding place for corrupt elements in the army," Xi was quoted as saying at a military political work conference this week in the northwestern city of Yanan, the founding stronghold of the Chinese Communist Party.

"Cadres at all levels, especially senior cadres, must show up, and have the courage to put aside their prestige and expose their shortcomings. They must deeply self-reflect ... make earnest rectifications, resolve problems at the root of their thinking."

The political tests currently faced by the People's Liberation Army (PLA) are "intricate and complex" and the national situation, party situation and military situation are "all undergoing complex and profound changes", Xi said in a keynote speech to military cadres, including Zhang Youxia and He Weidong, the second and third-in-command of the PLA.

Xi also vowed to "enrich the toolbox for punishing new types of corruption and hidden corruption" and to strengthen the supervision of senior cadres.

China's military has undergone a sweeping anti-corruption purge since last year, with nine PLA generals and at least four aerospace defence industry executives removed from the national legislative body to date, including from the strategic PLA Rocket Force which oversees tactical and nuclear missiles. A handful of other defence industry bosses have been dismissed from the country's political advisory body.

The former Chinese Defence Minister Li Shangfu was removed from the website of the Central Military Commission, the Party's highest military command body, in February after being ousted as defence minister without explanation last October. Reuters reported that he was under investigation for corrupt procurement of military equipment.

The three-day conference, which ended on Wednesday, was the first of its kind since 2014, when Xi held another military political work conference in Gutian on the anniversary of a meeting which consolidated Mao Zedong's control over the Red Army, the PLA's precursor.

It takes place weeks before the long-delayed Third Plenum, a key meeting of the Communist Party's central committee which will discuss economic reforms as well as formally remove disgraced members. The exact dates have not been announced yet. Li Shangfu and ousted former foreign minister Qin Gang remain members of the central committee.

The purges are a setback for Xi, who has pumped billions into buying and developing equipment as part of a modernising drive to build a "world-class" military by 2050 - as military tensions in the South China Sea and the Taiwan Straits have become more fraught.

Since he took power in 2012, he has embarked on a widespread anti-corruption crackdown among Communist Party and government officials, with the PLA being one of the main targets.

China's defence ministry last year vowed to "crack down on every corrupt official".