<< A police vehicle on patrol in the Tibetan autonomous Garze Prefecture in Sichuan province, China.

They said the monks in Sichuan province, bordering Tibet, demonstrated close to where another monk set himself on fire last week to protest against China's 58-year rule of the Himalayan region.

Scores of monks at Aba prefecture's Sey monastery rallied after officials outlawed prayers during a traditional Buddhist festival, the US-based International Campaign for Tibet (ICT) said, citing sources there.

"Several hundred monks marched from the monastery after officials banned them from praying, calling to be allowed to celebrate the Monlam prayer festival and for authorities to release all Tibetan prisoners," the group said.

It said armed police had surrounded the monastery after the monks returned there and it was now likely to be under a lockdown, although it had no more information.

The New York-based Students for a Free Tibet also reported on Sunday's rally, saying between 300 and 400 soldiers tried to stop the protest as the monks marched out of the monastery.

"The monastery is now sealed and there is a heavy military presence outside the main road," the group said in a statement.

Tensions are high in Tibetan-populated areas ahead of the March 10 anniversary of the failed 1959 uprising against Chinese rule that ended with revered spiritual leader the Dalai Lama fleeing into exile.

Tibetans also took to the streets on March 14 last year, after four days of peaceful protests to mark the uprising's 49th anniversary.

A woman resident reached by phone by AFP confirmed the Aba protest, while government officials and police said they had not heard about any incident.

"Yes, monks protested yesterday morning. I don't know what they wanted," the resident said, declining further comment.

Several other locals reached by phone refused to speak. Activist groups have reported that residents in Tibetan areas have been threatened with detention if they talk to foreign reporters.

The Dalai Lama, other exiles and activist groups have reported a massive security build-up in Tibet and neighbouring areas with Tibetan populations ahead of the uprising anniversary.

The Dalai Lama has accused Chinese authorities of trying to provoke Tibetans into demonstrating to justify a huge crackdown.

Tibet's exile leaders say Beijing's response to last year's unrest left 200 Tibetans dead. China says police killed one "insurgent" and blamed Tibetan "rioters" for 21 deaths.

Security forces opened fire on protesters in Aba during last year's upheaval, killing at least seven Tibetans, activist groups said.

On Friday last week, a monk set himself on fire near the Kirti monastery, several kilometres from the Sey monastery.

The monk, in his late 20s, was shot after dousing himself with petrol and setting himself alight, the London-based group Free Tibet said.

Chinese authorities on Monday denied police had shot the man, and said he was in a stable condition in hospital, according to a Xinhua report.

The report said the monk's name was Tashi, or Tapey in Tibetan, and he was aged 24. It said he tried to set himself alight while holding a portrait of the Dalai Lama and the Tibetan independence flag.

Police "immediately put out the fire and sent the young man to hospital," where he remained in a stable condition, Xinhua said.

Getting independent information from Aba and other Tibetan-populated areas is extremely difficult. Travel agents told AFP foreign tourists are banned from visiting Tibet in March and foreign media are barred indefinitely.