China risks dangerous instability unless it embraces democratic reforms to limit the power of the ruling Communist Party, foster competitive voting and rein in censors, the Party's top think-tank has warned in a new report.

The "comprehensive political system reform plan" by scholars at the Central Party School in Beijing argues for steady liberalisation that its authors say can build a "modern civil society" by 2020 and "mature democracy and rule of law" in later decades.

The cost of delaying this course could be economic disarray and worsening corruption and public discontent, they write in "Storming the Fortress: A Research Report on China's Political System Reform after the 17th Party Congress".

"Citizens' steadily rising democratic consciousness and the grave corruption among Party and government officials make it increasing urgent to press ahead with demands for political system reform," the report states. "The backwardness of the political system is affecting economic development."

The report was finished in October, just after the Party's twice-a-decade congress ended and gave President Hu Jintao five more years as party chief. But it is only now appearing in some Beijing bookstores.

This is no manifesto for outright democracy. The authors say the Party must keep overall control and "elite" decision-making will help China achieve lasting economic prosperity by pushing past obstacles to economic reform.

But the 366-page report give a strikingly detailed blueprint of how some elite advisers see political relaxation unfolding, with three phases of reform in the next 12 years, including restricting the Party's powers and expanding the rights of citizens, reporters, religious believers and lawmakers.

"Until now political reform has been scattered and inconsequential," Wang Guixiu, a professor at the Party School not involved in the study, told Reuters. "Real political reform needs a substantive plan of action, and there are some scholars and officials who believe that's what is needed now."

The authors include Zhou Tianyong and Wang Changjiang, senior reform-minded scholars at the School, which trains officials for higher office. The report also has a preface by Li Junru, a government adviser and vice president of the Party School.

Several authors contacted for comment declined to comment.

UNSETTLING SOCIAL CHANGES

The authors argue that government regulation of news is needed as China navigates unsettling social changes. But the present system of secretive and often arbitrary censorship is stoking corruption and public distrust of government, they said.

"Freedom of the press is an inevitable trend," they said, calling for a law to protect reporters and "effectively halt unconstitutional and unlawful interference in media activities".

They also urge greater official respect for religion - a sensitive topic in China, where the atheist Party is wary of growing numbers of Christians, and unrest in Buddhist Tibet and the largely Muslim region of Xinjiang in the country's far west.

"Political faith and religious faith are not in contradiction," the scholars said.

They propose that China's nearly 3,000-delegate national parliament be slimmed down and given direct powers to set the budget and audit government spending.

Candidates for legislatures should be allowed to actively compete for votes, which is now banned, the authors said. And the Communist Party itself must bind itself under rule of law.

Communist Party chief Hu has promoted limited "inner-Party democracy" to expose officials to more checks, but has shown no appetite for broad political liberalisation.

In a speech on Monday, Hu said the Party had to be a "staunch leadership core" that maintained "flesh-and-blood bonds" with the people, Xinhua news agency reported.

But the Party School report, with its detailed arguments for change, and other books and essays from reformist advisers in the past year, suggest that some senior advisers have been thinking closely about much more ambitious reforms.

A recent survey of mid-ranking officials studying at the Party School indicated that growing numbers believe deeper political reform is needed.

In the survey of 154 officials conducted in late 2007, 55.5 percent nominated the "political system" as one of three areas of reform that most "concerned" them, according to a study recently published by the Chinese Academy of Social Sciences.

In late 2005, 40 percent of officials surveyed listed political reform as one of the areas.