Chinese security forces fired tear gas to break up a protest by Tibetans in the southwest province of Sichuan, an advocacy group said, the latest sign of spreading unrest in the region.
Reports from advocacy groups earlier said that in a separate clash, coinciding with this week's Chinese New Year celebrations, troops fired on thousands of Tibetans protesting in the same province, killing at least one and wounding more.
Free Tibet, a London-based organisation that campaigns for Tibetan self-determination, said in an email that on Monday troops fired tear gas at Tibetan protesters in Meruma township, Aba County, called Ngaba County by Tibetans.
"Tibetans had gathered to protest Chinese oppression on the occasion of Chinese New Year, having decided that they would not celebrate the lunar New Year because of the current repression in Tibet," Free Tibet said.
"Additional security forces have been deployed in the area and roads connecting Ngaba to the surrounding counties have been closed by the authorities."
This year the main Tibetan traditional new year celebrations begin on Feb. 22; the Han Chinese Lunar New Year celebrations began on Sunday.
The confrontation in Aba came on the same day that, according to two advocacy groups, Chinese troops in another part of Sichuan's mountainous western edge fired on thousands of Tibetan protesters, killing at least one and wounding more.
Calls by Reuters to police in Aba on Tuesday were not answered, but an official in a court there said: "You should not believe in rumours."
"People say all kinds of things to get attention, but they're not all true. Wait for the government to explain the situation," said the official, who would not give his name.
The western part of Sichuan province where the recent unrest has been concentrated is dominated by ethnic Tibetans and lies next to the official Tibetan Autonomous Region .
It has long been a source of protest against Chinese rule, and is the site of a recent string of self-immolations, mostly by Tibetan Buddhist monks.
Free Tibet said the deadly shooting happened after protesting Tibetans gathered in Luhuo, about 590 km (370 miles) west of Sichuan's capital of Chengdu, and marched on government offices, where security forces opened fire.
The Tibetans were protesting about arrests earlier in the day in connection with the distribution of pamphlets carrying the slogan "Tibet Needs Freedom" and declaring that more Tibetans were ready to stage self-immolations to challenge Chinese rule, the group said in an emailed statement.
One resident -- a 49-year-old Tibetan man called Yonten -- was shot dead by government forces and another 30 or so residents were injured, said Free Tibet.
Another advocacy group, the International Campaign for Tibet, said three people were killed and about nine injured when police fired into the crowd in Luhuo, which is called Drango or Draggo by Tibetans.
Chinese security forces have been on edge after 16 incidents of self-immolation by ethnic Tibetans over the last year in response to growing resentment of Beijing's controls on religion. Some have called for the return of the Dalai Lama, the exiled Buddhist leader revered by many Tibetans.
China's Foreign Ministry has branded the self-immolators "terrorists" and has said the Dalai Lama, whom it condemns as a supporter of violent separatism, should take the blame.