But the party stressed that its absolute leadership was at the core of rule by law, the main theme of the gathering.

"The party should rule the country according to the constitution, and it has to govern the party with internal party rules," the statement said.

According to the constitution, the NPC is the top legislature, although it is often seen by the outside world as a rubber-stamp body that represents the consensus of top party decision makers.

Mainland analysts said the party's emphasis on the constitution was entirely different from the Western-style concepts of constitutionalism and separation of powers.

By upholding the role of the constitution, the party was not undermining its own supremacy, but consolidating it, analysts said.

Zhang Lifan , a Beijing-based political commentator, said that by pledging to deal with violations of the constitution, the party would be regulating the behaviour of local public servants, thereby solidifying its own position.

"By upgrading the [NPC's] mechanism to deal with violations of the constitution, the Communist Party wishes to consolidate its power by regulating the governing style of local bureaucrats," Zhang said. "This would also ease social tension arising from rampant injustice and corruption."

The plenum document also said the party would hold judges responsible for life for incorrect rulings. It promised to make court proceedings more transparent, and to root out officials who used personal influence or bribes to meddle with the justice system.

The party also vowed to expand judicial independence by appointing more professional and experienced judges and prosecutors, and giving them greater power to make decisions.

In addition, the document said the party would use legislation to better protect the rights of citizens and would involve the public more in the legislative process.

While mainland media were quick to applaud the party's decisions, some legal scholars were more cautious.

They said that despite the emphasis on rule of law, the party had hedged its words carefully in recent documents and in its statement yesterday.

The party has often said that rule of law is necessary because it would help improve the ability of the party to govern. And in an internal document last year, the party called on the official media to avoid using such concepts as citizens' rights, universal values and constitutional democracy.

Zhiqun Zhu, professor of political science and director of the China Institute at Bucknell University, in the US state of Pennsylvania, said the party's interpretation of rule of law differed from those elsewhere because it insisted the goal should be achieved under the party's leadership and according to socialism with Chinese characteristics.

"How to keep and justify the delicate relationship between the party and law? As the party tries to strengthen China's legal system, its most difficult job is balancing the need to maintain the party's authority and promote judicial independence," Zhu said.

Steve Tsang, chair of the University of Nottingham's School of Contemporary Chinese Studies, said Xi was using the constitution and the law to support and strengthen party rule.

Under this approach, Tsang said, "human rights as a whole will improve, but the rights of dissidents or 'enemies of the state' will suffer much more".

Tong Zhiwei , a law professor at Shanghai's East China University of Political Science and Law, said: "The decision showed the ambition of the Communist Party to push for rule by law … But in reality it will be a long process to instigate real change."