MIDNIGHT DEADLINE
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.
Dilxat Raxit, spokesman for the exiled World Uighur Congress, says that there was a heavier police presence in Hetian, Kashgar and other parts of Xinjiang.
"Now, if you are a group of more than three or four, you can't congregate together," he said by telephone.
Residents contacted in Lhasa said the city was under tight police watch ahead of a Monday midnight deadline for protesters to give themselves up. Qiangba Puncog said calm was returning.
Foreign reporters are barred from travelling to Tibet without official permission and tourists have been asked to leave.
A Reuters reporter in Sichuan 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.
In Machu in the province of Gansu, a crowd of 300-400 carried pictures of the Dalai Lama 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 a 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 military crackdown.
"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 Kenneth Lieberthal, a political scientist at University of Michigan.
Speaking from his home in India's Himalayan foothills on Sunday, the Dalai Lama called for an investigation into what he called cultural genocide in Tibet.
Xinhua news agency quoted Tibetan officials as saying the Nobel peace laureate's charge was "downright nonsense" and trumpeted China's development policies in Tibet. Critics say those policies favour Han Chinese migration to the region, contributing to a huge wealth gap between Chinese and Tibetans.
