In a report released on Monday, Human Rights Watch also accused China of trumping up charges of bombing against a jailed Tibetan Buddhist monk in order to muzzle him.
The organisation said the persecution of Tenzin Delek Rinpoche, a highly-respected Tibetan lama, highlighted the ongoing strictures placed on Tibetans in China.
HRW said the case against Tenzin Delek, given a suspended death sentence in December 2002 over a rash of bombings in a Tibetan-populated area of the southwest, was riddled with inconsistencies and procedural flaws.
Its report - based on nearly 150 interviews - said the government targeted Tenzin Delek after a decade of trying to curb his social and spiritual work.
And to convict him it had to force a confession from the co-defendant who named him.
The group demanded the immediate release of the monk and a handful of other Tibetans arrested in connection with his case.
"Human Rights Watch is concerned that the Chinese government's treatment of Tenzin Delek is not an isolated phenomenon," the report said.
"In spite of China's rhetoric about legal reform, Tenzin Delek's case shows that when it comes to Tibet, the Chinese government still does not tolerate uncontrolled political or religious activity," Mickey Spiegel, a researcher in the Asia Division of Human Rights Watch, added in a statement.
"In spite of China's rhetoric about legal reform, Tenzin Delek's case shows that when it comes to Tibet, the Chinese government still does not tolerate uncontrolled political or religious activity"
Human Rights Watch
The Foreign Ministry had no immediate comment. However, China typically rejects statements by foreign human rights groups as attempts to meddle in its internal affairs, saying its citizens are dealt with according to law.
Despite heated protests from international rights groups and diplomats, China executed Lobsang Dondrup, the other Tibetan tried alongside Tenzin Delek, last January.
In a tape released at the time and said to have been smuggled out of jail, Tenzin Delek protested his innocence from his cell, where he remains today.
In China, a suspended death sentence is usually commuted to life imprisonment.
Beijing has shown intermittent signs of increasing tolerance towards the Tibet region in the past two years, freeing several prominent activists and allowing a series of rare visits by envoys of spiritual leader the Dalai Lama.
But many devout Tibetans resent what they see as Chinese occupation and interference in their religious lives since the People's Liberation Army marched in and imposed Communist rule in 1950.
In recent years, the Chinese government has consolidated secular control at the expense of monastic influence.