China has warned the United States not to use religious incidents as a pretext to interfere in its domestic affairs, after Washington said it was “seriously concerned” that more Tibetans have set themselves on fire in China.

U.S. State Department spokeswoman Victoria Nuland said Monday the recent wave of self-immolations shows there is enormous anger over severe Chinese restrictions on human rights and religious freedoms.

In response, a Chinese Foreign Ministry spokesman (Liu Weiman) warned Wednesday against the United States using “religious affairs” as grounds for political interference. He also insisted the Beijing government safeguards the basic rights of ethnic groups, including their religious freedom.

Witnesses and human rights groups say three Buddhists protesting against Chinese rule in Sichuan province have self-immolated in the past week and that two of them have died.

At least 15 Tibetan Buddhists are believed to have set themselves on fire in the past 10 months, since a young monk protesting Chinese rule died after self-immolating outside the Kirti monastery last March.

That death sparked months of protests by monks and nuns and triggered a major Chinese crackdown that included the arrests and disappearances of hundreds of monks.

Beijing has denounced the self-immolations and accuses Tibetan exiles of encouraging them. The government says Tibetans enjoy religious freedom.