China insisted on Monday that it had shown massive restraint in the face of violent protests by Tibetans, which it said were orchestrated by followers of the Dalai Lama to wreck Beijing's Olympic Games in August.
But even as the governor of Tibet told reporters in Beijing that no lethal weapons had been used against protesters in the city of Lhasa, troops poured into neighbouring provinces to quell copycat protests and riots that erupted over the weekend.
A resident in Sichuan province's Aba prefecture said fresh protests flared in two Tibetan schools on Monday, with hundreds of students from each facing off against police and troops.
The resident, who declined to be named because he feared for his safety, told Reuters by telephone that 18 people -- including Buddhist monks and students -- were killed when troops opened fire with guns on Sunday, and a policeman was earlier burnt to death.
His account could not be immediately verified.
Exiled representatives of Tibet in Dharamsala, India, on Sunday put the death toll from last week's protests in Lhasa, capital of the Himalayan region of Tibet, at 80.
But Qiangba Puncog, the government chief in Tibet, said that only 13 "innocent civilians" were killed and dozens of security personnel were injured in Lhasa when several days of monk-led protests broadened into riots in which houses and shops were burned and looted last Friday.
"I can say with all responsibility we did not use lethal weapons, including opening fire," he told a news conference in Beijing, adding that only tear gas and water cannon had been used to deal with the region's worst protests in nearly two decades.
The governor said the unrest was planned and organised by "external and domestic forces" of the "Dalai clique", referring to Tibetan Buddhists' exiled spiritual leader, the 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."
The Dalai Lama fled Tibet after a failed uprising against Chinese rule in 1959 and set up a government-in-exile in Dharamsala. Beijing reviles him as a separatist though he says he only wants more autonomy for the region, which Communist troops entered in 1950.
Tibet is one of several potential flashpoints for the ruling Communist party at a time of heightened attention on China ahead of the Olympic Games.
The government is concerned about the effect of inflation and wealth gaps on social stability after years of breakneck economic growth, and this month it said it had foiled two plots hatched by the members of the Muslim Uighur population in the northwestern region of Xinjiang, including an attempt to disrupt the Olympics.
Residents contacted by telephone in Lhasa said the city was under tight police watch on Monday ahead of a midnight deadline set by the authorities for protesters to give themselves up.
Qiangba Puncog said calm was returning to the city.
Foreign reporters are barred from travelling to Tibet without official permission and tourists have been asked to leave.
A Reuters reporter in Sichuan province said he saw columns of trucks filled with armed troops on the roads.
In the Aba region, two ethnic Tibetans said hundreds of People's Liberation Army vehicles moved in overnight, after unrest in which police said a crowd of protesters had hurled petrol bombs, torching a police station and a market.
"They've been driving through all night. It's just tailing off now," the man said, adding that word had spread of protests in other parts of the region as well.
In Gansu province's Machu town, a crowd of 300-400 carried pictures of the Dalai Lama and shouted slogans at the weekend as they marched on government buildings, breaking windows and doors and setting fire to Chinese shops and businesses, the Free Tibet Campaign said.
The London-based group said 100 Tibetan students staged a sit-in at Northwest Minority University in Gansu's capital, Lanzhou, a worry for a country with a history of student unrest, notably the Tiananmen Square protests of 1989 that ended in a bloody military crackdown.