Hong Kong (CNN) -- A nun has died after setting herself on fire in southwestern China, the first Tibetan woman known to have killed herself in this way, the London-based Free Tibet campaign group said Tuesday.
According to the group, Tenzin Wangmo, 20, called for religious freedom in Tibet and for the return of the Dalai Lama as she set fire to herself outside Dechen Chokorling Nunnery in Ngaba County, Sichuan Province on Monday.
She died at the scene.
The State Administration for Religious Affairs in Beijing told CNN they were not aware of the incident.
Free Tibet, which advocates Tibetan independence, also reported that two Tibetans were shot and wounded on Sunday by security forces during a protest outside a police station in the prefecture of Ganzi.
Tenzin is the ninth Tibetan -- all monks or former monks -- to commit self-immolation in protest against Chinese rule since March, the advocacy group said. Five have died.
The last attempt took place on Saturday when a 19-year-old former monk from Kirti monastery in Aba, another ethnic Tibetan area in Sichuan province, set himself alight in the central market in Ngaba Town but survived.
His whereabouts are unknown, according to Free Tibet.
Activists say the disturbing acts reflect an increasingly repressive environment under Beijing's control.
"Most Tibetans live in fear because of suppressive and unfair government policies but they dare not speak up," prominent Tibetan writer and activist Tsering Woeser told CNN.
"Tibetan Buddhists can't use violence to protest, therefore they can only do violence to themselves, such as self-immolation, to make people pay attention to their situation.
"This is not suicide, this is sacrifice in order to draw the world's attention."
Another incident in Aba in March, in which a monk died, sparked weeks of often violent confrontation between local monks and authorities. Security forces locked down the Kirti Monastery and eventually detained more than 300 monks, rights groups said at the time.
When the United Nations working group on enforced disappearances expressed its concern to Beijing, Chinese officials called the organization's perspective "biased and unfair."
"The relevant local authorities are conducting legal education for the Kirti Monastery monks to maintain religious order there -- there was no question of forced disappearances," Hong Lei, a foreign ministry spokesman, said in June.
China also rejects accusations of oppression of Tibetans, saying its rule has greatly improved living standards for the Tibetan people.
The Dalai Lama's representative signed an agreement with Beijing in 1951 to affirm China's sovereignty over Tibet but also grant autonomy to the area. A failed uprising against Beijing's rule in 1959 forced the Dalai Lama into exile.
The Dalai Lama denies seeking independence for Tibet, saying he wants genuine autonomy, under which Tibetans can make their own policies on key issues, such as religious practices.
In a 2008 uprising, violent unrest in Tibet and the subsequent military crackdown left at least 18 dead, and activists say tensions have remained high in many areas since then.
CNN's Xiaoni Chen contributed to this report.