U.S. House Speaker Nancy Pelosi gave support to the Tibetan cause on a visit to the Dalai Lama, calling China's crackdown "a challenge to the conscience of the world."
Her criticism added to a chorus of international concern over Beijing's harsh response to the anti-government protests, as China sought to blame supporters of the Tibetan spiritual leader for unrest that is posing the biggest challenge in two decades to Beijing's control of Tibet.
"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 told a cheering crowd in Dharmsala, India, seat of the Dalai Lama's government-in-exile.
She dismissed China's claim that the Dalai Lama was behind the violence in Lhasa, the Tibetan capital, as making "no sense."
Meanwhile, Republican presidential hopeful Sen. John McCain said Friday that China is harming its world image with its crackdown in Tibet and expressed hope Beijing would seek a peaceful solution to the crisis.
"The people there are being subjected to mistreatment that is not acceptable with the conduct of a world power, which China is," McCain said while in France to visit President Nicolas Sarkozy
China's response to last week's riots in Lhasa drew world attention to its human rights record and threatens to overshadow its attempts to project an image of unity and prosperity ahead of the Aug. 8-24 Olympics in Beijing.
China's official news agency issued an updated casualty toll late Friday for the unrest in Lhasa. Xinhua said 18 civilians and one police officer died and 623 people were injured.
Tibetal exile groups have said 99 people were killed - 80 in Lhasa and 19 in Gansu province. Casualty estimates are hard to confirm because China keeps tight control over information.
On Friday, Chinese authorities intensified a manhunt for the wanted suspects, posting their photos - taken from video cameras and security footage - on major Internet portals.
Shown under the heading of "Lhasa Public Security Bureau's Wanted List of Criminal Suspects," the 21 people are accused of endangering national security, and cited for beating, smashing, looting and arson. One suspect is shown wielding a long sword and another is a mustached man who had been shown on news programs slashing another man with a foot-long blade.
The official Xinhua News Agency said two of the 21 suspects had already been arrested and a third turned himself in. Authorities called on the public for help, offering rewards for information and guaranteeing the anonymity of tipsters.
So far, police have arrested a total of 24 people and 170 others turned themselves in, Xinhua has said.
The protests in Lhasa - a stunning show of defiance against 57 years of Chinese rule - sparked sympathy demonstrations in neighboring provinces, prompting Beijing to deploy thousands of troops across a wide swath of western China where more than half of China's 5.4 million Tibetans live.
Moving from town to town, police set up blockades and checkpoints to keep Tibetans in and journalists out. The mobilization helped authorities reassert control after protests flared in Sichuan, Qinghai and Gansu provinces.
In Lhasa on Friday, residents said police were patrolling the streets and people were free to go where they wanted as long as they had identity cards.
An employee of the local Coca-Cola distributor said the business was closed. "Nobody dares to go out," said the man, who didn't give his name for fear of retribution.
Residents in Ganzi county in Sichuan province said Friday that they saw troops, trucks and helicopters on patrol in an area where hundreds of protesters took to the streets earlier this week.
In the largely Tibetan town of Zhongdian, in the far north of Yunnan province, some 30 armed police with clubs marched in the main square. Two dozen trucks carrying riot police had arrived overnight, reinforcing some 400 troops already in the area bordering Tibet.
Armed encampments were set up in nearby towns, including the tourist attraction of Tiger Leaping Gorge.
In Xiahe, a city in Gansu province that saw two days of protests, the 50-room Xilin Hotel was "completely occupied by police with guns and batons," said a hotel worker.
"There may be hundreds in our county right now. No tourists are allowed here and we do not feel safe going outside," said the man, who also refused to be identified for fear of reprisals.
He said things had calmed down but vehicles were patrolling the streets and authorities were asking Tibetans who took part in demonstrations to surrender.
A resident of Qinghai province, meanwhile, said about 300 troops were in the town of Zeku a day after monks protested outside the county government office. The woman, who did not want to give her name in fear of harassment by authorities, said she did not dare leave home: "Many ethnic Chinese dare not to go out. Only Tibetans do."
Demonstrations in Lhasa began peacefully March 10, the anniversary of a failed 1959 uprising by Tibetans, but erupted into violence March 14, drawing a harsh response from Chinese authorities.
Xinhua said Thursday that police shot and wounded four rioters "in self-defense" during violent protests Sunday in Aba county in Sichuan. It was the first time the government acknowledged shooting any protesters.