His warning followed repeated anonymous online calls for pro-democracy rallies in big mainland cities over the past three weeks. Although no protests or mass gatherings were reported, jittery authorities have been on high alert, with tens of thousands of uniformed and plain-clothes police deployed in shopping districts and thoroughfares in Beijing, Shanghai and a dozen other cities on the past three Sundays.

Wu also categorically rejected the notion of separation of powers or any moves to copy Western-style democracy, dashing hopes for political reform following renewed discussion in recent months. Intriguingly, in a departure from past practice, Wu criticised not just calls for ideological pluralism, but also further privatisation, which he added to the list of threats to one-party rule.

'We have made a solemn declaration that we will not employ a system of multiple parties holding office in rotation; diversify our guiding thought; separate executive, legislative and judicial powers; use a bicameral or federal system; or carry out privatisation,' he said.

Analysts said the warnings on pluralism and privatisation were aimed at consolidating the party's iron grip on power in a bid to guard against different opinions, especially the rise of calls for liberal democracy that have emerged after the unrest in Egypt, Tunisia and Libya.

'The party is clearly worried about rising political demands and ideological confusion among the people and its party members in the wake of the 'jasmine revolution',' veteran Hong Kong-based China observer Johnny Lau Yui-siu said.

The possible convergence of growing appeals for greater democracy and widespread grievances over rising food and housing prices, corruption and pollution has apparently hit Beijing's most sensitive nerve.

The message from Wu and other mainland officials who have spoken out about the issue is simple: Communist Party rule is essential to stability and to prevent the country from descending into the chaos that has swept across the Arab world.

'That is why we have seen that while the government talks at great length about sharing the benefits of economic growth to ease discontent on one hand, it steps up the clampdown on political dissent on the other,' Lau said.

Professor Zhang Ming, a political scientist at Beijing's Renmin University, said Wu's ultra-orthodox remarks represented the views of party conservatives.

'Those remarks may sound familiar, but clearly they carry specific meanings in the light of the domestic political situation as well as the events in the Arab nations,' he said.

But Lau and Zhang both said it was confusing to say that Beijing would not support privatisation after more than 30 years of reform and opening up.

Private ownership has increased strongly since the early 1990s as many small and medium-sized state-owned enterprises, mostly in less efficient heavy industrial sectors at local levels, have been privatised.

But privatisation has long been opposed by party conservatives who are concerned about the loss of state assets and millions of laid-off workers.

State media have reported that the number of registered private enterprises on the mainland topped 8.4 million last year, accounting for 74 per cent of the country's total.

Analysts said that what Wu said appeared to be at odds with eye-catching remarks by Premier Wen Jiabao last year on the necessity of political reform.

Wen's remarks caused a stir among party liberals and internet intellectuals.

During a high-profile trip to Shenzhen ahead of the 30th anniversary of the establishment of the country's first special economic zone in August, Wen warned that the fruits of economic reform would be lost and the goal of modernisation would not materialise without the safeguard of political reform.

While Wen still talked about 'active yet prudent' political reform in his work report last week, party conservatives like Wu and Jia Qinglin, chairman of the Chinese People's Political Consultative Conference, have stepped up the rhetoric against such reform.

'Their different remarks have laid bare disagreement between Wen and other leaders like Wu,' Zhang said.

Although Wen's liberal, populist remarks were largely a repetition of appeals by paramount leader Deng Xiaoping before the bloody June 4 crackdown on pro-democracy protesters in 1989, analysts said they were quite unusual given the party's mainstream conservative views towards Western-style democracy.

'Wen's views can be best viewed as his personal opinions, aimed at setting up a populist image, but clearly what Wu said represents a broader consensus within the central government,' Lau said.