Chinese authorities are threatening severe punishment of protesters in Tibet who do not surrender by Tuesday.
A notice in official media says demonstrators will face unspecified measures if they do not turn themselves in.
The warnings were made as Tibet's India-based exiled government reported at least 30 people were killed in Friday's violent protests in Lhasa. Other reports say as many as 100 people have been killed. Chinese authorities put the death toll at 10.
U.S. Secretary of State Condoleezza Rice Saturday called on the Chinese government to exercise restraint in responding to the protests and to release detained monks and other demonstrators.
Also Saturday, protesters sympathizing with the demonstrators in Tibet took to the streets in more than half a dozen countries, including the United States, China, Nepal, Australia and Switzerland.
Many of those demonstrations turned violent, including in China, Nepal and Australia. Police in New York City reported injuries among both police officers and protesters after demonstrators reportedly threw rocks at the Chinese consulate.
Witnesses say calm returned to Lhasa Saturday where a strong Chinese security presence is trying to maintain order.
Tibet's government-in-exile has called on the United Nations for intervention to stop the violence in Tibet.
From his home in exile in Dharamsala, India, Tibet's spiritual leader, the Dalai Lama, appealed for both sides to avoid violence.
He said the demonstrations in Lhasa represent long-standing resentment of Chinese rule, and he has counseled Beijing to address protests with dialogue, not force.
A group of Polish lawmakers warned the Chinese ambassador to Poland Saturday that the country could pull out of the Olympics to protest China's crackdown.
Human Rights Watch and Amnesty International Friday called for the U.N. to conduct an independent investigation of China's actions.
China has controlled Tibet since 1951. The Dalai Lama and thousands of his followers fled to India from Tibet in 1959 during the failed revolt against Chinese rule.