Chinese troops were out in force on Sunday in the Tibetan city of Lhasa, after a week of peaceful protests against Chinese rule culminated in riots on Friday.
Cars and houses were reportedly being searched as large parts of the city were effectively shut down.
Tibetan sources say that as many as 80 people were killed during the unrest, though Chinese authorities said just 10 people had died.
Chinese authorities encouraged demonstrators to give themselves in by midnight on Monday (1600GMT), promising leniency to those who surrendered.
Meanwhile, in the Indian town of Dharamsala, exiled monks prayed at a session attended by the Dalai Lama, who called for an international investigation into the unrest in Tibet.
And on Dharamsala's streets, activists protested against what the Dalai Lama called China's "rule of terror" and "cultural genocide" in Tibet.