A top human rights group says the news that a Tibetan Buddhist nun set herself on fire and died shows a “new level of desperation” against Chinese policies in the region.

An Amnesty International official, Sam Zarifi, said Tuesday Chinese authorities should heed the demands of Tibetans to freely practice their religion and enjoy their culture. Instead, he said China has resorted to a “heavy handed” response that he said can further fuel resentments.

Zarifi called for the immediate release of Tibetans imprisoned for protesting Chinese policies.

The Tibetan exile network, known as Free Tibet, said the nun, 20-year-old Tenzin Wangmo, was the ninth Tibetan and first woman to set herself on fire this year.

The U.S. State Department reacted Tuesday to her death by expressing serious concern about self-immolations by Tibetan monks. A spokesman urged Chinese leaders to respect the rights of Tibetans, and to protect the Tibetans' “unique religious, cultural and linguistic identity.”

China routinely rejects criticism of its treatment of minorities, calling it interference in its internal affairs.

Free Tibet reported that the nun died Monday after lighting herself on fire in Sichuan province near the Tibetan border.