The Dalai Lama has launched a fierce attack on Chinese rule in his Tibetan homeland, saying his people had experienced "hell on Earth".
Five decades of Chinese rule had caused "untold suffering", Tibet's exiled spiritual leader said, accusing Beijing of creating a climate of fear.
He also repeated his demand for Tibet's "legitimate and meaningful autonomy".
His words came on the 50th anniversary of a failed uprising against Chinese troops which led to his exile.
The BBC's James Reynolds in Beijing says that the Dalai Lama's words were different from his usual peaceful comments.
This is perhaps a sign of the exasperation and frustration he must feel over China's stance, our correspondent says.
China says its troops freed Tibetans from effective slavery in a feudal society. It is planning to mark 28 March - the day in 1959 on which the Communist Party dissolved the existing local government in Tibet - as Serfs' Emancipation Day.
Chinese Foreign Ministry spokesman Ma Zhaoxu described the Dalai Lama's statement as "lies".
"The Dalai Lama clique is confusing right and wrong. They are spreading rumours. The democratic reforms [under Chinese rule] are the widest and most profound reforms in Tibetan history," he said, quoted by AFP news agency.
On Monday, President Hu Jintao called for a "Great Wall" against Tibetan separatism.
Thousands of Chinese troops and paramilitary police are said to have been deployed in Tibetan-populated regions amid fears of fresh violence on the sensitive anniversary.
Campaign groups have already reported some unrest in areas around Tibet. China does not allow foreign journalists unrestricted access to Tibet or restive areas surrounding it, making it extremely difficult to verify these reports.
Beijing says it has tightened its border controls in preparation for "expected sabotage activities by the Dalai Lama clique".
But there have been demonstrations around the Asia-Pacific region.
Four people were arrested in clashes with police outside the Chinese embassy in the Australian capital Canberra but later released.
In Nepal about 100 Tibetan exiles were blocked by police outside Kathmandu, as the government imposed a ban on protests outside the Chinese embassy, AFP news agency reported.
The Dalai Lama said hundreds of thousands of Tibetans had been killed, and thousands of places of worship destroyed.
But the two sides needed to work for "mutual benefit".
"We Tibetans are looking for legitimate and meaningful autonomy, an arrangement that would enable Tibetans to live within the framework of the People's Republic of China," the exiled leader said.
"I have no doubt that the justice of Tibet's cause will prevail."
The Dalai Lama paid tribute to all those who had died since 1959, including victims of last year's deadly protests in Lhasa that spilled over into other ethnic Tibetan regions.
Successive Chinese campaigns - class struggle, the Cultural Revolution and "patriotic re-education" - had "thrust Tibetans into such depths of suffering and hardship that they literally experienced hell on earth", he said from his seat in exile in India's Dharamsala.
"Even today Tibetans in Tibet live in constant fear and the Chinese authorities remain constantly suspicious of them."
Tibet's religion, culture, language and identity were "nearing extinction", he said, and Chinese development was devastating the Tibetan environment and way of life.
He repeated an accusation that China has killed "hundreds of thousands of his people".
"Many infrastructural developments... which seem to have brought progress to Tibetan areas were really done with the political objective of Sinicising Tibet," he added.
China has always denied any mass killings of Tibetans.
Referring to his "Middle Way approach" - offering to accept Chinese sovereignty in Tibet in return for genuine autonomy - the 73-year-old leader expressed disappointment that China had "not responded appropriately to our sincere efforts".
But he said the two sides should "look to the future and work for our mutual benefit".
"Fulfilling the aspirations of the Tibetan people will enable China to achieve stability and unity," he added.
The latest round of stop-start talks with Beijing last November concluded with China condemning the Tibetans' proposals as a bid for "disguised independence".
Our correspondent says it is very difficult to see where progress can happen at the moment.
In a separate statement, the Tibetan government-in-exile pledged to continue to push the "Middle Way approach" but said the continuation of contact depended solely on China.