Chinese security forces used both brutal beatings and lethal force against protesters during unrest in Tibet in 2008, a rights group says.
Many of the protesters who were subsequently detained were beaten and tortured, Human Rights Watch said.
The report from the US-based group was based on interviews with 203 Tibetan refugees outside China.
China has blamed Tibetan "separatists" for inciting the violence and denies that excessive force was used.
The unrest in March 2008 was the worst in Tibet for 20 years. Violence erupted in Lhasa on 14 March, shortly after the anniversary of a failed revolt against China in 1959.
China says rioters killed at least 19 people, most of them Han Chinese, but Tibetan exiles say security forces killed dozens of protesters. The violence then spread to ethnic Tibetan areas outside Tibet.
In the wake of the unrest Tibet was closed to foreigners and tens of thousands of Chinese soldiers sent to the region.
BBC News
