The US on Tuesday called on China to engage in an unconditional substantive dialogue with the Dalai Lama and his representatives to resolve the Tibet issue.
"We call on the Chinese government to engage in substantive dialogue with the Dalai Lama, with his representatives, and without preconditions," State Department spokesman Patrick Ventrell told reporters.
This has been the longstanding policy of the US, he said.
"We are very concerned by the self-immolations, detentions, arrests of family members and associates of those who have self-immolated," Ventrell said when asked about the recent self-immolation bids in Tibet in which more than 100 people have died so far.
The question of human rights was raised by US secretary of state John Kerry in his meeting with the Chinese leadership during his just concluded trip to China, he said.
Meanwhile, Radio Free Asia said Chinese security forces have detained 21 Tibetans following clashes with police over the forced demolition of recently rebuilt homes in an earthquake-hit region of northwest China's Qinghai province.
At least six Tibetans and four policemen were injured in the clashes today after a protest by over 100 area residents angered by the demolition of Tibetan homes in the town of Kyegudo in the Yulshul (in Chinese, Yushu) Tibetan Autonomous Prefecture, a local source, speaking on condition of anonymity, told RFA's Tibetan Service.
"When the police cracked down on the Tibetan protesters, the Tibetans clashed with police, and six Tibetans and four policemen were injured in the clash," the source said.
"So far, the authorities have detained 21 Tibetans and taken them away," he said.
Kyegudo was hit by a devastating earthquake on April 14, 2010, that largely destroyed the town and killed almost 3,000 residents by official count.
Now, Chinese authorities have begun to demolish rebuilt Tibetan homes, saying their occupants are not officially registered to live in the town, sources said.