China set a "surrender" deadline after riots in Lhasa that it said killed 10 innocent people, launching a crackdown on Saturday after the worst unrest in Tibet for two decades.
The response came after torrid protests on Friday which flew in the face of official claims the region was immune from unrest as Beijing readies to hold the Olympic Games in August.
Xinhua news agency said 10 "innocent civilians" were shot or burnt to death in fires that accompanied street clashes in the remote, mountain capital on Friday. It said no foreigners died, and the dead included two people killed with shotguns.
Tibetan law-and-order departments offered leniency for rioters who turned themselves in by Monday midnight.
"Criminals who do not surrender themselves by the deadline will be sternly punished according to the law," stated the notice on the Tibetan government Web site (www.tibet.gov.cn). It added that those who "harbour or hide" them also face harsh treatment.
The government offered rewards and protection for informers.
Chinese television showed footage of rioters trashing shops and trying to break down the entrance of a bank, and plumes of smoke floating above the city.
A source close to the self-proclaimed Tibetan government-in-exile suggested China's death toll of 10 was not the full story. He said at least five Tibetan protesters were shot dead by troops. Other groups supporting Tibetan independence have claimed many more may have died.
The Olympic torch arrives in Lhasa in a matter of weeks.
China has accused followers of Tibet's exiled spiritual leader, the Dalai Lama, of masterminding the rioting, which has scarred its image of national harmony in the build-up to the Beijing Olympics.
A rash of angry blog posts appeared after China confirmed deaths in Lhasa and Hollywood actor Richard Gere, a Buddhist and an activist for Tibetan causes, suggested an Olympic boycott.
Tibetan crowds in the remote mountain city attacked government offices, burnt vehicles and shops and threw stones at police on Friday in bloody confrontations that left many injured.
A Reuters picture showed a protester setting afire a Chinese national flag. Another depicted security personnel shielding themselves against rocks hurled by protesters.
