ZHONGDIAN, China - The government stepped up its manhunt Friday for protesters in last week's riots in the Tibetan capital, as thousands of troops converged on foot, in trucks and helicopters in Tibetan areas of western China.

The violence in Lhasa - a stunning show of defiance against 57 years of Chinese rule - has sparked sympathy demonstrations in neighboring provinces, prompting Beijing to blanket a huge area with troops and warn tourists and foreign journalists to stay away.

China's communist leadership, embarrassed by the chaos and international criticism of its response, has blamed the unrest on the Dalai Lama and his supporters and vigorously defended its reputation as a suitable host for the Beijing Olympics.

On Friday, House Speaker Nancy Pelosi met with the Dalai Lama in India and called on the world to denounce China's crackdown in Tibet.

Photos of 21 men wanted in connection with the Lhasa riots were posted on major Chinese Internet sites.

A resident in Qinghai province said about 300 troops were in the town of Zeku after monks protested Thursday outside the county government office. The woman, who did not want to give her name for fear authorities would harass her, said she did not dare leave her home and could not provide details of the demonstration.

Telephones at Zeku's government and public security bureau rang unanswered.

In the largely Tibetan town of Zhongdian, in the far north of Yunnan province, some 30 armed police with batons marched in the main square as residents went about their daily life. Overnight, another two dozen trucks of riot police had arrived, adding to a presence of about 400 troops.

Patrols had also been set up in other nearby towns, including the tourist attraction of Tiger Leaping Gorge.

In Xiahe, a city in Gansu province where there were two days of protests last week, the 50-room Xilin Hotel was "completely occupied by police with guns and batons," said a man who answered the telephone and did not want to give his name.

"No tourists are allowed here and we do not feel safe going outside," the man said. He said things had calmed down but vehicles had been patrolling the streets asking Tibetans who had participated in last week's demonstrations to turn themselves in.

Residents in Ganzi county in Sichuan province said they saw troops, trucks and helicopters on patrol.

The massive mobilization of riot police was helping authorities reassert control after the broadest, most sustained protests by Tibetans against Chinese rule in decades. Demonstrations had flared across Sichuan, Gansu and Qinghai provinces in support of protests that were started in Lhasa.

Led by Buddhist monks, protests began peacefully early last week but erupted into rioting on March 14, drawing a harsh response from Chinese authorities.

Numbers for injuries and death tolls have been varied and hard to confirm because China keeps a tight control over information. Tibetan exile groups say 99 people were killed - 80 in Lhasa and 19 in Gansu - while Beijing maintains that 16 died and more than 300 were injured in Lhasa.

The official Xinhua News Agency said Thursday that police shot and wounded four rioters "in self defense" during violent protests on Sunday in Aba County in Sichuan. It is the first time the government has acknowledged shooting any protesters.

The crackdown drew worldwide attention to China's human rights record, threatening to overshadow Beijing's attempts to project an image of unity and prosperity in the lead-up to the Aug. 8-24 Olympics.

Pelosi, one of the fiercest Congressional critics of China, called on the international community to denounce Beijing's handling of the anti-government protests.

"If freedom loving people throughout the world do not speak out against China's oppression in China and Tibet, we have lost all moral authority to speak on behalf of human rights anywhere in the world," Pelosi said before a crowd of thousands of cheering Tibetans in Dharmsala, the seat of the Dalai Lama's government-in-exile.

Pelosi, heading a Congressional delegation, was greeted warmly by the Dalai Lama, who draped a gold scarf around her neck.

On Thursday, the White House said President Bush will still attend the Games but Secretary of State Condoleezza Rice urged restraint when she spoke to Chinese Foreign Minister Yang Jiechi.

Xinhua said Yang blamed the Lhasa riots on the Dalai Lama's supporters.

"They attempted to exert pressure on the Chinese government, disturb the 2008 Beijing Olympics and sabotage China's social stability and harmony," it cited Yang as saying.

In Lhasa on Friday, residents said police were still patrolling the streets and people were free to go where they want as long as they had identity cards.

An employee of the local Coca-Cola distributor said the business was still closed. "Nobody dares to go out," said the man who didn't give his name for fear of retribution.

A woman who answered the telephone at the Religious Affairs Bureau said the Sera and Drepung monasteries, whose monks launched the initial protests, were still closed. The Jokhang temple, Tibet's most sacred shrine and the heart of Lhasa's old city, was also shuttered, she said.

Late Thursday, state broadcaster China Central Television aired a 15-minute program showing how Tibetan rioters rampaged through Lhasa last week but none of the ensuing police crackdown.

Video from security cameras showed burned shops, wounded Chinese and a knife-wielding Tibetan standing atop a police car. Buddhist monks were shown throwing sticks and other debris at riot police in a scuffle on March 10, in an attempt to portray the protests as having been started by monks.

The photos of the 21 men posted on the Internet appeared to be taken from videos and cameras and were shown under the heading of "Lhasa Public Security Bureau's Wanted List of Criminal Suspects for Beating, Smashing, Looting and Burning."

The images included a man with a mustache who has been shown on news programs slashing at another man with a foot-long blade. Another suspect wielded what appeared to be a long sword.

Two had already been arrested and one turned himself in, Xinhua said. Authorities were offering rewards and guaranteed the anonymity of tipsters for the rest.

The Lhasa Public Security Bureau refused to comment on the photos.