The speaker of the U.S. House of Representatives, Nancy Pelosi, called on the world community Friday to denounce China in the wake of its crackdown in Tibet, calling the crisis "a challenge to the conscience of the world."

Pelosi, one of the fiercest Congressional critics of China, was the first major official to meet the Dalai Lama, the leader of Tibet's exile community, since protests turned violent last week in the Chinese-ruled region.

"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, including monks and schoolchildren.

"The situation in Tibet is a challenge to the conscience of the world," she said.

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

"I pray for success of the speaker of such a great nation, considered a champion of freedom, democracy and liberty," the Dalai Lama said, standing next to Pelosi.

After meeting with the Tibetan leader, Pelosi called for an international investigation into the violence in Tibet and said the Chinese should open the region to the international media and independent monitors.

She dismissed China's accusations that the Dalai Lama was behind the violence as making "no sense."

Rep. James Sensenbrenner of Wisconsin, the ranking Republican on the trip, also expressed his support for the Tibetan people.

"In the U.S. Congress, there is no division between Democrats and Republicans on the issue of protecting Tibetan culture and eliminating repression against Tibetans around the world," he said.

Hundreds of people lined the roads to the Dalai Lama's compound, some with signs saying "Thank You for Your Support" and "Long Live America-Tibet Friendship." About 2,000 more people waited in the temple's main courtyard, many waving Indian, U.S. and Tibetan flags.

Kalsing Phuntsok, 37, a teacher who was in the crowd welcoming Pelosi, called her "a very good friend of Tibet."

"America has a big role to play, a very big role," he said.

The visit was planned before protests against Chinese rule turned violent last week in the Tibetan capital, Lhasa, sparking a brutal crackdown by Beijing.

"Perhaps it's our karma, our fate, to be with you at such a sad time," Pelosi said. "It is our karma, we know, to help the people of Tibet."

"Today we are here at this sad time together in shedding the bright light of truth on what is happening inside Tibet," Pelosi said. "We insist the world know what the truth is inside Tibet."

Thousands of Chinese troops have converged in Tibetan areas of western China, ready to clamp down on any signs of further unrest.

A spokesman for Tibet's government-in-exile said 19 Tibetans have died in China's Gansu province in recent days following anti-government protests, raising the total death toll in the region to 99.

Spokesman Thuten Samphel provided no details on how the 19 people died.

China says 16 people have been killed since anti-government protests turned violent in the Tibetan capital last week.

Chinese officials have accused the Dalai Lama and his supporters of organizing violent clashes in Tibet in hopes of sabotaging this summer's Beijing Olympics and promoting Tibetan independence.

The protests have been the biggest challenge in almost two decades to Chinese rule in Tibet.