A Chinese official has rejected reports that protests have taken place in a Tibetan area of south-west China.
"There were no such riots as some foreign media have reported," state media quoted Wu Zegang, head of Aba prefecture in Sichuan, as saying.
Tibet campaigners say at least two monk-led protests have taken place in Aba in recent days.
Tension is said to be high in some Tibetan areas ahead of the 50th anniversary of the Dalai Lama's exile.
Last year, deadly riots broke out in Lhasa a few days after the 10 March anniversary of the anti-China uprising that led to the Tibetan spiritual leader's flight to India.
It is extremely difficult to independently confirm any information coming out of Tibetan areas. China's authorities have restricted access to the region.
Campaign groups have been reporting protests in Aba since last week.
China has confirmed that a monk holding a picture of the Dalai Lama set himself on fire in Aba on Friday.
China says Tibet was always part of its territory
Tibet enjoyed long periods of autonomy before the 20th Century
1950: China launched a military assault
Opposition to Chinese rule led to a bloody uprising in 1959
Tibet's spiritual leader, the Dalai Lama, fled to India
But local government officials denied campaigners' reports, citing witnesses, that the monk had been shot. Police had doused the fire and taken him to hospital, state-run Xinhua news agency said.
Campaigners said hundreds of monks were present at the protest.
The International Campaign for Tibet said a second demonstration occurred on Sunday at the Sey monastery. Security personnel had blocked a monks' prayer meeting, triggering a protest.
The monks were now surrounded in their monastery, ICT said.
The monastery was now sealed and there was a heavy military presence outside the main road, New York-based Students for a Free Tibet also said.
Addressing the Chinese People's Political Consultative Conference, the top advisory body that meets once a year, senior Communist Party official Jia Qingling said ethnic unity should be strengthened.
"We unequivocally supported the party and government in dealing with the destructive, disruptive, violent and illegal incidents in Lhasa, Tibet, and other areas in accordance with the law," Mr Jia said.
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