The announcement by the Foreign Ministry at a hastily called news conference came as about 40 students staged a sitdown protest at the Central University for Nationalities in Beijing, marking the spread of pro-Tibetan demonstrations to the capital.

'The Chinese government will unwaveringly protect national sovereignty and territorial integrity,' ministry spokesman Liu Jianchao said, calling on other countries to protect its diplomatic personnel.

China said on Monday it had shown great restraint in the face of violent protests by Tibetans, which it said were orchestrated by followers of the Dalai Lama seeking to wreck the Beijing Olympics in August.

But even as the governor of Tibet said no guns were used against protesters in Lhasa, troops poured into neighbouring areas to enforce control as the regional capital counted down to a midnight deadline for protesters to give up.

'If the Tibetans in Lhasa take to the streets again in large numbers and really challenge the Chinese authorities, I think we'll see a very harsh crackdown,' said Mr Kenneth Lieberthal, a political scientist at the University of Michigan.

The continued tensions ensured the violence of the past week in Tibet would hang over the country no matter what the resolution, with foreign protests, pleas for leniency and China's crackdown weighing uncomfortably on the build-up to the Games.

The European Union condemned the violence but said a boycott of the Olympics would not be the right answer.

Russia said it hoped China would do what was necessary to curtail 'unlawful actions' in Tibet.

A brief Russian Foreign Ministry statement made no criticism of Beijing.

Dalai Lama

Tibet governor Qiangba Puncog said the protests were ignited by supporters of the exiled Dalai Lama.

'This time a tiny handful of separatists and lawless elements engaged in extreme acts with the goal of generating even more publicity to wreck stability during this crucial period of the Olympic Games - over 18 years of hard-won stability,' he said.

There have been daily pro-Tibet protests around the world since last Monday.

On Sunday, French police used tear gas against around 500 demonstrators at the Chinese embassy in Paris, and there were incidents at missions in New York and Australia.

'We strongly condemn the violent action of Tibet independence activists,' Mr Liu said, denouncing attacks on its missions abroad. Of the violence in Tibet, he said: 'This shows the international community the Dalai clique.'

The Dalai Lama has said he supports the Beijing Games and has outright rejected the Chinese allegations about his role.

He fled Tibet after a failed uprising against Chinese rule in 1959 and set up a government-in-exile in Dharamsala, northern India. Beijing reviles him as a separatist but he says he wants only real autonomy for the region, which Communist troops entered in 1950. The last major rioting in Tibet was in 1989.

Fresh Protests

An ethnic Tibetan in Sichuan's Aba prefecture said fresh protests also flared near two Tibetan schools on Monday, with hundreds of students facing off against police and troops.

About 40 students from a high school for Tibetans in Maertang county, Aba, were beaten and arrested for protesting, the Dharamsala-based Tibetan Centre for Human Rights and Democracy later said. Repeated calls to the school went unanswered.

The resident, who asked not be identified, also said 18 people, including Buddhist monks and students, were killed when troops opened fire on Sunday.

Earlier, a policeman was burnt to death, he said. His account could not be immediately verified.

Another Tibetan said the area was tense and few dared go out.

'There was talk that hundreds of nuns protested too, but when you're locked up at home, who can tell?' he said. He also said a dozen or more people died in the violence on Sunday.

Exiled representatives of Tibet in Dharamsala on Sunday put the protest death toll at 80.

But Qiangba Puncog said only 13 'innocent civilians' had been killed and dozens of security personnel injured in Lhasa when several days of monk-led protests broadened into riots in which houses and shops were burned and looted on Friday.

'I can say with all responsibility we did not use lethal weapons, including opening fire,' he said in Beijing. Tear gas and water cannon were used to quell the region's worst protests in nearly two decades, he said.

Peng Xiaobo, who sells clothes in Lhasa, told state television that seven family members were forced to leap from an upper floor when a mob set his ground-floor shop on fire.

A member of the People's Armed Police was beaten unconscious by a mob, one of whom then used a knife to carve out a chunk of flesh the size of a fist, said Qiangba Puncog.

A passer-by was burnt alive after petrol was poured over him, he also said.

Residents contacted in Lhasa said the city was under tight police watch ahead of a Monday midnight deadline for protesters to give themselves up. -- REUTERS