Tenzin Delek was one of China’s most high-profile political prisoners, and his death and hasty cremation are likely to aggravate tensions in a region already bristling with anti-government sentiment.

On Monday, the police were said to have fired tear gas and live ammunition into a crowd of more than a thousand people who had gathered outside government offices in Nyagchuka, a largely Tibetan town in Sichuan where Tenzin Delek had once lived. More than a dozen people were wounded, according to Students for a Free Tibet, an overseas advocacy group that reported the confrontation.

Geshe Jamyang Nyima, the cousin, said prison officials had allowed Tenzin Delek’s sisters to view his body Thursday morning shortly before it was cremated at a secret prison outside Chengdu. “They found that his lips and his fingernails had turned black,” said the cousin, who lives in exile in India and is in frequent phone contact with one of the sisters. “To us, it is clear he has been murdered.”

Tenzin Delek was a revered figure among Tibetans in Sichuan, where he helped build medical clinics, schools and monasteries. He was also known as an environmentalist who opposed mining and deforestation.

But his promotion of Tibetan language and culture — and his devoted following among local residents — made Chinese officials uncomfortable, according to Padma Dolma, campaigns director for Students for a Free Tibet. “He wasn’t involved in political activities, which is why it was such a shock when he was arrested and charged with conspiring to plant a bomb,” she said.

After his arrest — and a secret trial — Tenzin Delek became known beyond Sichuan. After international rights advocates campaigned for his release, his death sentence was commuted to life in prison, though a co-defendant was executed in 2003.

Robert Barnett, director of the modern Tibet studies program at Columbia University, said the Chinese government had been quietly granting medical parole to ill Tibetan prisoners, including 17 over the past two years. But given Tenzin Delek’s popularity, he said, the authorities may have feared public celebrations over his release.

“That he was allowed to die in prison is really quite extraordinary,” he said. “It’s something that is going to be very strongly felt in Tibetan communities.”