Hundreds of paramilitary police aboard at least 80 trucks traveled along the main road winding through the mountains into southeastern Tibet. Others set up camp and patrolled in riot gear, helmets and, for a few, rifles in the area above Tiger Leaping Gorge, a tourist attraction that usually sees little unrest.
Such scenes were repeated across far-flung towns and villages in Tibetan areas of adjacent provinces to reassert control as sporadic demonstrations continued to flare. Foreigners were barred from traveling there and tour groups were banned from Tibet, isolating a region about four times the size of France.
The protests against Chinese rule started peacefully in Tibet's capital, Lhasa, early last week, but erupted into riots last Friday, drawing a harsh response from Chinese authorities. Authorities say 325 people were injured and 16 people died.
The official Xinhua News agency reported Thursday that police shot and wounded four protesters "in self defense" over the weekend in western Sichuan province. It is the first time the government has acknowledged shooting any protesters in nearly a week of unrest.
China says the riots and protests were plotted from abroad by the Dalai Lama, the exiled spiritual leader revered by Tibetans, and his supporters. They have denied Tibetan exile groups' claims that 80 died in the violence and ensuing crackdown.
Speaking from the seat of his government-in-exile in Dharmsala, India, the Dalai Lama reiterated that he was not seeking independence for Tibet. He offered to meet with Chinese President Hu Jintao and other Chinese leaders, though said he would not travel to Beijing unless there was a "real concrete development."
"The whole world knows Dalai Lama is not seeking independence, one hundred times, thousand times I have repeated this. It is my mantra -- we are not seeking independence," the 72-year-old Dalai Lama told reporters.
"The Tibet problem must be solved between Tibetan people and Chinese people," he said.
The Foreign Ministry expressed "grave concern" over a planned meeting between British Prime Minister Gordon Brown and the Dalai Lama, telling Brown not to offer support to the exiled leader.
At a tense news conference, Foreign Ministry spokesman Qin Gang said the government suggested that foreign tourists stay out of western Gansu and Sichuan provinces, the scene of additional clashes earlier this week between Tibetan protesters and security forces.
After a long pause, he added: "But I shall assure you that our government is fully capable of maintaining social stability and ensuring the security of tourists."
In Sichuan's Aba county, a Tibetan woman reached by phone Thursday said she had heard of numerous arrests of protesters in the area.
"There are many, many troops outside," she said. "I'm afraid to leave the house," said the woman, who refused to give her name for fear of retaliation by authorities.
Police were checking ID cards at checkpoints and could be heard shouting for protesters to turn themselves in.
Troops blocked roads also in nearby Serthar, also in Sichuan, confining residents to their homes, said a woman reached there by phone.
The London-based Free Tibet Campaign reported that troops had been sent to the county after local residents blew up a bridge near the village of Gudu.
Protests were reported also in neighboring Qinghai province, which is heavily Tibetan.
The official Xinhua News Agency said the protesters attacked shops and government offices on Sunday in Aba, known as Ngawa in Tibetan, but made no mention of allegations by pro-Tibet groups abroad that troops fired on protesters, killing several.
Zhang Yusheng, a spokesman for the Gansu provincial government, said a "small number of lawbreakers shouted reactionary slogans, raised the flag of separatism and adopted violent methods."
Shops, schools, homes, vehicles and government offices in Gansu's Gannan prefecture -- a predominantly Tibetan area -- were attacked, posing an "extremely grave threat" to social order, Zhang was quoted by state media as telling reporters on Wednesday.
Reinforcements were brought in and order was restored, he said. He mentioned no arrests.
Despite those reassurances, a hotel receptionist in the regional center of Luqu said employees and guests had been holed up inside since Tibetan protesters marched through the area on Sunday.
"The streets are now filled with police officers. Our hotel is booked out with tourists, but no one feels safe enough to set foot outside," said the woman, who refused to give her name or that of her hotel for fear of retaliation by authorities.
A police officer in the nearby town of Maqu refused to answer questions about the situation.
The reports confirm previous claims by Tibetan exile groups that the protests had spread. Foreign journalists have been banned from going to Tibet and have found it increasingly difficult to travel to areas in other provinces with Tibetan populations.
The Tibet Daily reported that 24 people had been arrested for endangering state security and for other "grave crimes" for their roles in last Friday's riots in Lhasa. Another 170 people have reportedly turned themselves in to police.
The protests have been the biggest challenge in almost two decades to Chinese rule in Tibet, a Himalayan region that the People's Liberation Army occupied in 1950 after several decades of effective independence.
But authorities appeared to be regaining control in Tibet and surrounding provinces where more than half of China's 5.4 million Tibetans live. Moving from town to town, police checked IDs and set up roadblocks to keep Tibetans in and reporters out.
On Thursday morning, an Associated Press photographer was turned away from a flight to Zhongdian in Yunnan province. There were 12 policemen, some with automatic weapons, at the check-in counter. The police said no foreigners were allowed to travel to Tibetan areas due to the protests.
The unrest has prompted discussion of a possible boycott of the Aug. 8 opening ceremony at the Beijing Olympics and calls for China to address Tibetans' grievances and engage in direct talks with the Dalai Lama.
Despite China's relentless vilification, the Dalai Lama -- winner of the 1989 Nobel Peace Prize -- remains widely revered by Tibetans, traveling widely and meeting an array of politicians and celebrities.
China has ignored calls for dialogue, casting recent events as evidence that the Dalai Lama could not be negotiated with.
Tibet's hard-line Communist Party boss Zhang Qingli this week labeled the Dalai Lama a "wolf in monk's robes" and said Beijing was in a "life-and-death" struggle with his supporters.
Adding to Beijing's worries, activists said Thursday they would demonstrate in Beijing during the Olympics to press China to help end bloodshed in Sudan's Darfur region.