Stacked up in Liu Yi's studio dozens of China's most sensitive subjects stare out from thick black-and-white oil paintings, from victims of Tiananmen Square to Tibetans who have set themselves on fire.

Liu, 50, is a rare example of a member of China's Han ethnic majority taking up the Tibetan cause -- a project that has finally brought the authorities to his door.

More than 100 Tibetans have set themselves alight, around 90 dying, to protest against what many call Beijing's oppressive rule, but most Han Chinese accept the government's stance that it has brought development and is combating tragic acts of violence.

"What they want is simply freedom of religion, of faith, and respect," said Liu, in a spare brick-walled studio at his home in an artists' community in eastern Beijing.

"One goal is to commemorate them," he said of his images. "Another is to let more people understand the truth in Tibet through these paintings, because nowadays, especially in China, people simply don't know what is happening."

He is provided with earlier photographs by a Tibetan writer but treats his 40 subjects as though he knew them personally, pointing out the first immolator, the youngest, and the first woman.

"This was a mother with four children... this one had a one-year-old child," he said, rushing between the sombre portraits.

Over the past 15 years growing numbers of Han Chinese have embraced Tibetan Buddhism -- including Liu -- but have not backed their political demands, says Columbia University Tibet expert Robbie Barnett.

Artists have drawn inspiration from Tibetan landscapes while devotees have even travelled to India to hear from the exiled Tibetan leader the Dalai Lama, whom Beijing denounces as a separatist encouraging immolations.

But the spiritual interest "seems not to affect political positions, certainly not openly", Barnett said in an email.

"For an ethnic Chinese artist to take up this project publicly is very unusual and high-risk, and I can't think of a precedent."

China has invested heavily in Tibetan areas to raise living standards but also imposed controls such as monitoring monasteries and banning images of the Dalai Lama.

It has also gone on the offensive to prevent immolations -- which the UN and overseas rights groups have blamed on repressive tactics -- by jailing those accused of inciting and abetting the acts.

Guards equipped with fire extinguishers are posted on Beijing's Tiananmen Square, their numbers boosted for China's current National People's Congress meeting, where the Tibetan delegates are hand-picked loyalists whose leader was seen wearing a Mao Zedong badge.

Han Chinese make up 91 percent of China's population and Barry Sautman, an expert on ethnic politics in the country, said while they may empathise with Tibetans and appreciate their culture, they also tend to trust the government on security matters.

The majority thinking runs along the lines of "the government is trying to do something for the Tibetans; on the other hand, the Dalai Lama is trying to get them to commit suicide", said Sautman, a professor at the Hong Kong University of Science and Technology.

Critics argue that China's development efforts have mainly benefited Han incomers while eroding Tibetan culture, and that other measures have inhibited religious practice and led to abuses such as disappearances and unfair trials.

Official Chinese data say that Han numbers in Tibet rose 56 percent from 2000 to 2010 and 92 percent in the previous decade, compared to 12 and 15 percent for Tibetans.

The census figures say Tibetans make up 90 percent of the region's population, but the Tibetan government-in-exile counters that, if traditionally Tibetan areas in the rest of China are included, their ethnic group is now "outnumbered".

Liu hopes to spread awareness of the Tibetan perspective through his latest collection, even though he knows it is unlikely ever to go on public display in China -- like his previous series commemorating prominent protesters.

These include victims of the crackdown on the Tiananmen Square demonstrations in 1989 and well-known dissidents whom he calls "China's conscience", among them jailed Nobel Peace laureate Liu Xiaobo.

A 4.5-metre-long mural shows photos of children propped up by rubble from the Sichuan earthquake in 2008, when many schools collapsed while other buildings did not, prompting angry accusations of corruption until discussion of the topic was suppressed.

Tibetan themes have attracted Liu since he began travelling to the region in the 1980s. He keeps a Tibetan dog and has painted countless Tibetan Buddhist images and many portraits of the Dalai Lama.

After his immolation paintings began drawing attention, he said, the authorities visited him three times in 10 days and tried to confiscate his work.

But he managed to dissuade them and is preparing to start his next batch of portraits -- this time on larger canvases.

"Unless they lock me up in prison, as long as I am free, then for sure I will keep painting," Liu said.

"I am definitely not afraid. Who am I compared to those self-immolators?"