Armoured troop carriers and tour buses packed with police roll along the winding mountain roads. Internet service is dead in some places. Military camps fortified with sandbags sit amid Tibetan communities, where strings of prayer flags flutter in the wind.

Armoured troop carriers and tour buses packed with police roll along the winding mountain roads. Internet service is dead in some places. Military camps fortified with sandbags sit amid Tibetan communities, where strings of prayer flags flutter in the wind.

Fifty years after a failed uprising sent the Tibetan leader, the Dalai Lama, into exile, China is mounting a show of force to try to prevent a repeat of last year's sometimes violent protests against Chinese rule. Tuesday marks the 50th anniversary of the March 10, 1959, revolt.

Last year, a commemorative march by monks in Lhasa, the capital of Tibet, was blocked by police. That set off protests, which erupted in an anti-Chinese riot on March 14 and then spread to dozens of Tibetan communities, embarrassing China before the Beijing Olympics.

In the year since, a kind of martial law has prevailed.

In Daofu, a town in Sichuan province where Buddhist mantras are carved into the sides of 13,000-foot (4,300-meter) mountains, monasteries are closed to visitors, their monks inside reading prayers, local officials said. Police cars patrol the streets.

"There have been thousands of police and troops here since the Lhasa riots last year. It has affected our lives," said one resident, who declined to give his name for fear of reprisals by local authorities. "Food is more expensive and harder to buy because the soldiers are eating a lot."

Amnesty International said Friday the region has been subjected to "a year of escalating human rights violations." The International Campaign for Tibet, a Washington-based group, says more than 600 people remain in detention, and the actual number is probably higher.

The Tibetan government-in-exile in India says 220 Tibetans died and nearly 7,000 were initially detained in last year's demonstrations. Beijing has not released an overall death toll, but says 22 died in Lhasa, most of them Chinese civilians.

China blames the Dalai Lama and his exile movement for fomenting the unrest to restore a Buddhist theocracy that communist rule overturned. Despite the Dalai Lama's repeated insistence he wants autonomy for Tibetans and not independence, the government on Saturday renewed its criticisms that he's a secessionist.

"Our differences with him are not over religious issues, human rights, democracy or culture," Foreign Minister Yang Jiechi told reporters in Beijing. "It is about whether we should defend China's unity and prevent Tibet from being separated from China's territory."

What is happening in Tibetan areas has become increasingly difficult to verify.

Foreigners have been barred from many Tibetan communities for much of the past year. Associated Press reporters were detained by police twice in recent days.

"This a sensitive period," said Yong Qing, a foreign affairs official in Daofu. She told the AP reporters they had to turn back because checkpoints and heavy snow made traveling deeper into Tibetan areas impossible. But she added, "Things are stable at the moment. We don't want that upset."

Internet and mobile phone text-messaging services — some of the ways that protesters organized last year — have been suspended in Sichuan's Tibetan areas of Aba and Ganzi, which have seen some of the fiercest protests.

"As far as I know, some of our service has been affected ... due to system maintenance there," said Lei Yu, a spokeswoman for China Mobile Ltd. in Hong Kong, the carrier's listed subsidiary. "We are making all-out efforts to resolve the problem, and I hope it will be done very soon."

Visitors to Lhasa in recent months have described swarms of armed police positioned across the city, some on rooftops, and blocking roads leading toward Sichuan.

But Legqog, a Tibetan government official, said Sunday that the build up of troops and police were temporary security measures against possible disturbances from Dalai Lama followers and foreign Tibetan rights groups.

"Most parts of Tibet are stable. People are living life as normal," Legqog, who like some Tibetans uses only one name, was quoted as saying by the official Xinhua News Agency at China's annual legislative session.

Even so, resistance continues. The advocacy group International Campaign for Tibet released photos Saturday of a wounded monk lying in the street of Aba after he set himself on fire to protest a ban on a key prayer festival. Days later, a group of monks from a nearby lamasery demonstrated on the same issue.

Not all monks agree with the protests. At a monastery south of Daofu, monks say last spring's violence was unnecessary. They were given thousands of dollars by the local governments for being an "exemplary" monastery.

"During the recent unrest in various places, our monastery was not willing to participate because we believe in 'love the country, love religion,"' said one monk, who was quoting a government line but did not want his name used. "We follow the instructions handed down by the Communist Party. Our teacher tells us every day that it's because of the Communist Party that we can have a new life."