The official number of people killed in protests in the Tibetan capital of Lhasa has risen to 19 dead and 623 injured, China's state media reported late Friday.
Xinhua reported the Tibet regional government as saying 18 civilians and one police officer were confirmed dead.
Those injured in the protests in Lhasa included 241 police officers and 382 civilians, Xinhua said. Previously, the official death toll was 13.
Tibetan exile groups have said 99 people were killed.
Thousands of troops were converging on Tibetan areas on Friday as the Chinese government stepped up its efforts to find protesters involved in last week's riots.
Riot police arrived on foot, by truck and by helicopter, blanketing a large part of Tibet and surrounding areas, the Associated Press reported.
The massive mobilization of troops was an attempt to regain control after the recent protests in the capital of Lhasa — the broadest demonstrations against Chinese rule in decades.
The photos of 21 men wanted in connection with the Lhasa riots were posted on major Chinese websites.
Violence in the capital spurred sympathy demonstrations in neighbouring provinces, including Sichuan, Gansu and Qinghai provinces.
The protests were led by Buddhist monks and began peacefully early last week but turned into rioting on March 14.
Also on Friday, U.S. House Speaker Nancy Pelosi met with the Dalai Lama in Dharamsala, India — the seat of his government-in-exile.
She called on the world 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.
Pelosi was heading a Congressional delegation on a trip scheduled before the riots broke out.
Tourists told to stay away in some areas
In Qinghai province, a resident said 300 troops were in the town of Zeku after monks protested Thursday outside the government office.
In the far north of Yunnan province, in the largely Tibetan town of Zhongdian, riot police in two dozen trucks arrived overnight, adding to a presence of about 400 troops.
Patrols were also set up in nearby towns, including at the tourist attraction of Tiger Leaping Gorge.
A 50-room hotel in another city in Gansu province where there were two days of protests last week was turning away tourists.
"No tourists are allowed here and we do not feel safe going outside," a man from the hotel said.
He said things had calmed down but troops were patrolling the streets in vehicles, asking Tibetans who had participated in last week's demonstrations to turn themselves in.
The numbers of dead and injured have varied since China has kept tight control over information.
On Thursday, the state Xinhua News Agency said police shot and wounded four rioters "in self-defence" during violent protests on Sunday in Sichuan — marking the first such admission by the government.
The newspaper said protesters set houses on fire, destroyed vehicles and lunged at police with knives.