In a report last week, U.N. High Commissioner for Human Rights Navi Pillay called on Beijing to address what she said was an alarming escalation in the number of protest suicides in Tibetan areas.
Pillay said she was disturbed by "continuing allegations of violence against Tibetans seeking to exercise their fundamental human rights of freedom of expression, association and religion."
Hong Lei, a spokesman for the Chinese Foreign Ministry, was quoted by state-run news agency Xinhua as saying Pillay's comments were seen as an assault in Chinese internal affairs.
"We are dissatisfied with and strongly opposed to the high commissioner's statement," he was quoted as saying.
He said the Tibetan people enjoy a relative sense of economic and social stability, saying a "clique" associated with the Dalai Lama, the Tibetan spiritual leader, has made false accusations against the Chinese government.
Pillay, in her statement, said she was disturbed by reports of forced disappearances and excessive use of force against Tibetan activists.
"I have had several exchanges with the Chinese government on these issues," she said. "But more needs to be done to protect human rights and prevent violations."