As Chinese security forces tighten control over Lhasa and other Tibetan towns, analysts trying to make sense of the worst anti-government protest in Tibet in decades are still puzzling over how things got so out of hand in the first place.

Hundreds of monks and local Tibetans rampaged through Lhasa, Tibet's capital city in remote western China, last Friday by smashing and burning buildings and cars. At least 16 people were killed.

The precise cause of the violence remains a mystery. But it is sufficiently well known that March is a sensitive time in Tibet, as the locals would find some way to mark the anniversary of a failed uprising against Chinese rule on March 10, 1959.

Experts said such activities in recent years, be they protest marches or demonstrations, tended to be small-scale affairs which the Chinese authorities kept under control with relative ease.

But this year, protest marches beginning on March 10 snowballed into tense standoffs with the security forces, and exploded into open rioting and looting last Friday.

Subsequent copycat demonstrations broke out in Tibetan towns in nearby Sichuan, Gansu and Qinghai provinces.

'What was extraordinary about the rioting was that it happened at all,' Stratfor, an intelligence agency, said in a report this week. 'The Chinese have confronted and contained Tibetan unrest with relative ease for years. (But) this time, the Chinese failed to contain events.'

Stratfor suggested that the Chinese government pulled its punches this year on worries that a heavy-handed approach would damage its international image ahead of the Beijing Olympics in August.

'They were hoping that it would die down on its own, leaving them time later to deal with the instigators. Instead it got out of hand, in a way very visible to the international media,' the Stratfor report added.

But Mr B. Raman, director of the Institute For Topical Studies in Chennai, India, contended that the unrest was not just a matter of miscalculation on Beijing's part.

He wrote in an online article: 'The revolt in Tibet and the incidents in Lhasa underline the total failure of the Chinese intelligence.'

Mr Raman, however, did not explain how this 'total failure' could have happened, particularly given the heavy presence of Chinese state security agents in Lhasa and the extensive resources at their disposal in the Tibetan capital.

Adding to the mystery, many analysts believe that Beijing ordered more troops into Tibet and Xinjiang last year precisely to ensure that these restive regions would not cause trouble ahead of the Olympics.

One conspiracy theory spreading on the political grapevine suggested that Beijing deliberately allowed the violence in Lhasa to flare up so that it could better identify the troublemakers and justify a major security operation in the region.

The late Chairman Mao Zedong used this tactic, loosely known as 'baiting the snake from its hideout', to devastating effect against his political opponents in 1957.

Veteran China-watcher Willy Lam said this theory was not entirely far-fetched, citing the 'well videographed' footage of the violent rioting in Lhasa shown on Chinese state television in recent days.

'It was good footage,' he added wryly. 'It is unimaginable, given the number of troops and police in Lhasa, that they could not have at least minimised the looting and burning.'

The Chinese government, however, blamed the rioting squarely on a 'premeditated plot' by Tibet's exiled spiritual leader, the Dalai Lama, and his associates.

China's official Xinhua news agency alleged on Tuesday that 'rogues and ruffians were even paid to join the riot'. They were rewarded for the destruction they caused, it added.

The Dalai Lama has denied the charges.

'We will never know if (the unrest) was instigated or not,' said Professor Tsering Shakya, a Tibet expert at the University of British Columbia in Canada. 'My feeling is that no one could have designed it on this scale.'

If the past week's unrest had indeed been the result of an intelligence failure, then President Hu Jintao and his proteges in the riot-hit regions may pay a political price for the incident, analysts said.

Mr Hu will suffer some loss of face and prestige in the ruling Chinese Communist Party, but the political career of Mr Zhang Qingli, the top official in Tibet and a prominent member of the President's power base, will dim considerably as a result, said Dr Lam, the Hong Kong-based China watcher.

There are no signs thus far that Mr Zhang, who was appointed Tibet's top official two years ago, would be held accountable for the current public relations disaster over Tibet.

He chaired a meeting of top Tibetan officials on Tuesday where he warned: 'We are engaged in a sharp battle of blood and fire with the Dalai Clique, a battle of life and death.'

chinhon@sph.com.sg

ADDITIONAL REPORTING BY SIM CHI YIN