Armed police fired on a crowd of locals and monks after some monks at the Tongkor monastery in Donggu township, an ethnically Tibetan area of western Sichuan province, were detained by police following a search for images of the Dalai Lama, the organisation said on its website (www.savetibet.org).

The monastery in Ganzi (Garze) Prefecture is home to 350 monks, according to its website (www.donggusi.com).

Phone calls to the monastery and local government bureaux were not answered.

On Friday, China's state-run Xinhua news agency said that 'an official was attacked and seriously wounded in a riot', adding that 'local officials exercised restraint' but did not give more details on the incident.

"Police were forced to fire warning shots and put down the violence, since local officials and people were in great danger," Xinhua said in its English-language report, which was also carried in the China Daily on Saturday.

Chinese language media did not carry news of the incident.

Ganzi and neighbouring Aba in Sichuan province have seen torrid confrontation between Tibetan protesters and police in past weeks. Anti-riot troops have poured into the area.

A mob armed with stones and knives killed an armed Chinese policeman in Ganzi late last month. On March 16, Buddhist monks and residents in Aba protested, demanding Tibetan independence from China. More than 200 police and officials there were hurt when violence broke out, a local official said this week.

The widespread unrest began in Lhasa, the capital of neighbouring Tibet province, and there officials on Friday vowed quick trials for those behind the unrest.

Lhasa was last month hit by Buddhist monks' protests against Chinese rule that gave way to deadly rioting on March 14, and since then security forces have poured in to reimpose control there and in other restive Tibetan areas.