By Karl Malakunas
BEIJING, March 21 - China stepped up its pressure on Tibetan protesters on Friday, releasing photos of wanted suspects who were captured on film in the worst rioting against Chinese rule in Tibet in nearly 20 years.
But with security forces having been poured into Tibet and other Tibetan-populated areas of China, rights groups and activists warned of mass arrests and the possible torture of those taken into custody.
With China keen to put its best face forward ahead of the Olympic Games in Beijing in August, US House of Representatives speaker Nancy Pelosi had harsh words for China as she met the Dalai Lama in India.
"The situation in Tibet is a challenge to the conscience of the world," said Pelosi, who was greeted by thousands of flag-waving Tibetan exiles as she arrived for talks Friday with Tibet's exiled spiritual leader.
"What is happening, the world needs to know," she said.
Faced with international concern over its handling of the unrest that erupted last week against Chinese rule in Tibet, state media acknowledged for the first time that police had opened fire on protesters.
After days of official statements that no lethal force had been used to quash the unrest, which has left an unknown number dead, state news agency Xinhua reported late Thursday that four people had been shot and wounded.
It said police shot the four in southwestern Sichuan province in "self-defence."
Pro-Tibet groups poured scorn on the report.
"At this point any statement the Chinese government puts out has virtually no credibility," said Lhadon Tethong from Students for a Free Tibet, based in Dharamshala, India.
"We are seeing photographs, we have friends who have lost relatives. We categorically reject any of the (official Chinese) information."
Officially, China has indicated that 13 people were killed in the rioting that broke out in the Tibetan capital, Lhasa, and spread to other areas. The victims, it said, were all innocent civilians killed by Tibetan "mobs."
But the Tibetan exile government of the Dalai Lama based in Dharamshala said it has confirmed 99 people were killed in the Chinese crackdown.
The protests began last week to mark the anniversary of a 1959 uprising against Beijing's rule of the vast Himalayan region, amid widespread anger over what Tibetans say have been brutal and repressive policies.
China has responded with a massive clampdown on the affected areas, and on Friday released a most-wanted list of 19 people caught on film taking part in the Lhasa riots, amid warnings by activist groups of harsh reprisals.
The photos, which appeared on top websites such as yahoo.com and sina.com, were taken from grainy footage taken during the unrest.
The state-controlled Tibet Daily later said two of the 19 alleged perpetrators had already been taken into custody. It also provided a hotline number for information from the public on those still at large.
"Lhasa police authorities are going all out to arrest the main suspects," the newspaper said.
The unrest has come at a sensitive time for China's rulers, with the Beijing Olympics fewer than five months away, and they have made huge efforts to stop the world from getting an independent view of their crackdown.
China has sealed off Tibet from foreign reporters and tourists, while releasing images and television footage of violent Tibetans.
Authorities have also sought to stop the foreign press from travelling to areas in Sichuan, Gansu and Qinghai provinces where protests have broken out.
However, foreign journalists, as well as Tibetan exiles and activist groups, have reported a huge military build-up in Lhasa and the other hotspot areas in recent days.
On Thursday, the last foreign journalist known to be in Lhasa reported that thousands of soldiers were in the streets.
"We saw a big convoy of military vehicles with troops in the back," Georg Blume, a journalist with German newspaper Die Zeit, told AFP shortly after being expelled.
Chinese authorities said on Thursday that 24 people had been arrested and 170 had surrendered for their involvement in the Lhasa unrest, following a house-to-house sweep of the city.
Tibetan exiled and activist groups warned the Lhasa crackdown was being repeated throughout the other provinces, and that the number of Tibetans now in custody was likely more than 1,000.
China says the Dalai Lama is behind the unrest, an allegation he has repeatedly denied.