China's grip on dissent in Tibet remains tight after deadly riots there in March, with more than 1,000 people still detained without charge, human rights group Amnesty International has claimed in a new report.
"Many hundreds, possibly thousands of Tibetans languish in prisons or detention centres without the government publicly acknowledging their whereabouts or formally charging them with a criminal offence," the report read.
Many were denied access to family and lawyers in a violation of international human rights conventions, it said.
"This is really a call to the Chinese government to actually provide that information and if people are detained, explain why they're being detained," Sam Zarifi, Amnesty's Asia-Pacific director, said in London.
"Either charge them and put them on fair trial or release them immediately," he added.
Amnesty's report called on Beijing to "release immediately and unconditionally those detained solely for engaging in peaceful protest, including support for the Dalai Lama, the independence of Tibet, or greater autonomy for Tibet."
The anti-China disturbances which broke out in Lhasa and nearby Tibetan areas posed the sharpest political challenge to Chinese rule in the mountain kingdom for decades, sparking global anti-China protests ahead of Beijing Olympics in August.
Amnesty also urged China to end an information blackout in Tibetan regions by granting free access to journalists and other foreign observers, including UN human rights experts.
The group said media coverage of the Olympic torch relay in the sensitive western region of Xinjiang should go unimpeded, with Uigher militants there accused by Beijing of working with al-Qaeda to push for an independent state.