Tsekho Tugchak, reportedly in his 40s, died in Ngaba county on Wednesday amid intensified security in the restive region ahead of the anniversary of a 2008 anti-China riot and 1959 independence uprising, the International Campaign for Tibet said.
ICT said his death was the 153rd self-immolation by a Tibetan since the protests began in 2009. The Free Tibet Campaign and US-backed Radio Free Asia also reported the death, saying it took place in Ngaba's Meruma township.
In Beijing, Tibet's Communist Party chief, the region's most powerful official, dismissed the reports.
"I don't think they're telling the truth," Wu Yingjie told reporters at a meeting on the sidelines of the annual session of China's ceremonial parliament.
The self-immolations by Tibetans monks, nuns and laypeople aim to highlight harsh Chinese rule and the oppression of Tibet's Buddhist culture, as well as appeal for the return of exiled spiritual leader, the Dalai Lama.
The region is closed to foreign media, making it virtually impossible to confirm reported self-immolations, which are believed to have peaked in 2012 with 83 that year.
Staff members reached at police headquarters, government offices and the local propaganda department in Ngaba, also known by its Chinese name, Aba, said they had no knowledge of the case. All declined to give their names as is usual among Chinese bureaucrats.
Many Tibetans insist they were essentially independent for most of that time and have protested what they regard as China's heavy-handed rule imposed after the People's Liberation Army's battled its way into the Himalayan region in 1950.
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