Tibet's government-in-exile on Saturday demanded the United Nations intervene to end what it called "urgent human rights violations" by China in the region following deadly protests.
The exiled government in Dharamshala in northern India, home to Tibetan spiritual leader the Dalai Lama, also said it had received "unconfirmed reports about 100 people had been killed and martial law imposed in Lhasa."
"The Tibetan parliament urges the UN to send representatives immediately and intervene and investigate the current urgent human rights violations in Tibet," the administration said in a statement.
Tanks and armoured vehicles were out in force in the Tibetan capital Lhasa on Saturday, a day after the worst protests against China's rule in the vast, Himalayan region in nearly 20 years, witnesses said.
China has said 10 people were burnt to death in the protests.
The exiled Tibetan government said it was "deeply concerned" by reports "emanating from all three regions of Tibet of random killings, injuries and arrest of thousands of Tibetans peacefully protesting against Chinese policy."
The protests reflect "the true sentiments of Tibetans inside Tibet and the yearning to be free from the repressive Chinese regime," it said.
Samdhong Rinpochehe, the government-in-exile's prime minister, urged China to "deal with this situation compassionately and with wisdom."
"The use of force by China has caused great disturbance to the Tibetans and we fear the Tibetans will lose the direction" of what has been a mainly non-violent freedom struggle, he told AFP.
Late Friday, the Dalai Lama had expressed "deep concern" over China's crackdown and urged Beijing to "stop using force" there and address the "resentment of the Tibetan people through dialogue."
"I also urge my fellow Tibetans not to resort to violence," said the Dalai Lama, who has stuck by his call for "cultural autonomy" rather than independence for Tibet despite ramping up his criticism of China in recent days.
A spokesman for the 72-year-old Dalai Lama denied Chinese charges that groups allied to the spiritual leader had "organised, premeditated and masterminded" the unrest.
"We can categorically say these kind of accusations are absolutely baseless and without any truth whatsoever," said the aide, Chhime R. Chhoekyapa.
"As far as we can see, these protests are spontaneous," he said.
Meanwhile, some 300 Buddhist monks, nuns and other Tibetan protesters took to the streets on Saturday in Dharamshala for more protests, police said.
"We're keeping a close watch on events," police superintendent Atul Phuljile told AFP in the town, where the Nobel peace laureate set up his government after fleeing Tibet in 1959 following a failed uprising against Chinese rule.
A group of 44 Tibetan exiles in India also set off on a fresh attempt to march on Saturday to their homeland from Dehra, 55 kilometres from Dharamsala.
The trek by mainly Buddhist monks and nuns began after Indian police on Thursday arrested 100 Tibetan marchers marking the 49th anniversary on March 10 of the Dalai Lama's escape to India following the abortive Tibetan uprising.
New Delhi has said it "does not permit Tibetans to engage in anti-China political activities in India" and has warned "any activity which causes disruption would be dealt with in accordance" with Indian law. (AFP)
Tibetan government-in-exile demands UN intervention