The military department responsible for buying China's weapons has launched a crackdown on corrupt procurement practices dating back years, issuing a call for tip-offs on "favouritism," collusion and other problematic behaviours.

The Central Military Commission's technology development body on Wednesday urged the public to report violations in procurement activities dating back to 2017, "in order to create a good ecosystem for equipment procurement, bidding and evaluation".

The CMC's Equipment Development Department posted on WeChat about eight types of violations targeted by the probe, including "actively leaking secrets", "lack of supervision" and "unfair handling of matters".

The department has long sought to weed out graft in its ranks, opening a special hotline in 2019 for reporting violations.

Wednesday's notice came the same day that Chinese President Xi Jinping called for increasing oversight of the military and the construction of a "modern system for military governance" in remarks to a meeting of top leaders.

Xi, who broke longstanding political precedent to seal a third term as China's leader last year, has made tackling corruption a centrepiece of his decade-long rule.

More than 1.5 million officials have fallen into the campaign's dragnet so far, according to official data.

Chinese authorities have depicted the policy as a much-needed cleansing of state organs, but critics contend that it is also a vehicle for Xi to purge political rivals.