(CNN) -- A Tibetan student who died after setting herself on fire in western China had been experiencing difficulties following a head injury, the official Chinese news agency reported Wednesday.
The student, Tsering Kyi, was the first of three Tibetans who reportedly self-immolated between Saturday and Monday. It is the only one of the three alleged acts so far acknowledged by the Chinese authorities.
Tibetan advocacy groups say the self-immolations -- more than 20 of which are reported to have taken place in the past year -- are to protest Chinese rule.
They follow an increase in security measures by the Chinese authorities in response to unrest among Tibetans in western areas of China in recent months and ahead of the sensitive anniversary of protests by Tibetan monks four years ago that ended in bloodshed.
Activists say the disturbing acts reflect an increasingly repressive environment under China's control. Beijing rejects accusations of oppression of Tibetans, saying that under its rule living standards have greatly improved for the Tibetan people.
Chinese officials have described the self-immolations as "extreme" acts. The report Wednesday by Xinhua, the government news agency, suggested Tsering Kyi, 20, had been troubled by the aftereffects of a head injury before she set herself on fire in the county of Maqu, or Machu in Tibetan, in Gansu Province.
"She was sent to hospital and has had occasional fainting spells," Xinhua reported, citing the local police. "The medical treatment held up her studies and her school scores began to decline, which put a lot of pressure on her and made her lose her courage for life and study."
A local official said similarities in the self-immolations point to a transparent political motive and behind-the-scenes orchestration, Xinhua reported. The victims were used by separatists to create chaos, according to Wu Zegang, chief of the Aba prefecture in Sichuan province.
On Sunday, a mother of four named Rinchen died after setting herself alight in front of Kirti Monastery in the county of Aba, which Tibetans call Ngaba, in Sichuan Province, according to Tibetan advocacy groups like London-based Free Tibet.
And on Monday, an 18-year-old Tibetan man named Dorje burned himself to death in a nomadic area of Aba, according to advocacy groups. Local officials reached by telephone declined to comment on the matter.
It was not possible to independently verify the accounts of the self-immolations. China restricts journalists' access to the areas where they have been taking place.
This month will mark the fourth anniversary of protest marches by Tibetan monks in Lhasa that ended violently in 2008.
Tibetans say the situation escalated to violence when Chinese police beat monks who had been protesting peacefully; Chinese authorities claim Tibetans launched attacks on Chinese businesses. Officially the death toll is under 20; Tibetans in exile say the death toll is near 150.