BEIJING - China’s ruling Communist party on Tuesday reaffirmed its supremacy over the country’s legal system, as it announced measures to centralise power and combat corruption following a highly-anticipated conclave.

The Communist party closely controls China’s parliament, police, prosecution and court systems, and anger over widespread injustice has emerged as an increasing problem for the party.

The principle of upholding the party’s leadership “must be adhered to” when implementing the rule of law, the party said in a 16,000-character statement carried by the official Xinhua news agency.

The principle was listed above equality before the law and upholding the rule of law in the document, which followed the Fourth Plenum meeting of the party’s Central Committee.

Party leader Xi Jinping, in a commentary issued by Xinhua alongside the decision, said it “made it clear that adhering to the party’s leadership is a fundamental requirement of socialist rule of law”.

Police in China often extort confessions with violence, while local officials routinely decide the verdicts of court cases in advance, sometimes because of bribes or political pressure.

Xi said the country was “troubled by unfair trials and corrupt judges”, adding that “some even go two ways by draining both the defendant and the plaintiff”.

Xinhua cited the Central Committee as saying: “Officials who intervene in law enforcement will ... face criminal charges if their conduct causes serious problems such as wrongful convictions.”

The Party will “strengthen the prevention from the origin of extorting confession by torture and illegal collection of evidence,” it said, without giving details.

Analysts have said that such measures could reduce the frequency of unjust verdicts, but implementation will be key and they are unlikely to apply in politically sensitive cases, such as the prosecution of dissidents or former officials.

The party document announced efforts to strip local governments of powers to issue legislation for their areas, and to step up corruption investigations, with a wider range of assets to be considered as potentially ill-gotten.

Official graft causes widespread public anger in China, and since taking office Xi - who proclaimed it a threat to the ruling party’s existence - has sought to present himself as a crusader against the scourge.

“Any major institutional or policy adjustments must be reported to the Party’s Central Committee for discussion before a decision is made,” Xinhua quoted the Central Committee as saying.

Authorities should not “make decisions with no legal basis”, it added.

“(We will) accelerate the national legislation on the fight against corruption... and set up an effective mechanism so that government officials dare not, can not and do not want to go corrupt,” it said without providing details.

China’s ruling party had cast the conclave last week as a pivotal moment for reform of the country’s legal system, and said that the theme of the meeting would be “rule of law”.

But experts caution that in China the phrase refers to a greater centralisation of control by the ruling party rather than a separation of powers, and had predicted the meeting would tighten the authorities’ grip.

China under Xi is also in the midst of a campaign against dissent, including several political prosecutions, that rights groups have called the harshest such crackdown in decades.