BEIJING — Three Tibetans killed themselves by self-immolation in two different Tibetan regions of western China over the past three days, to protest China’s repression of Tibet, according to reports by Tibetan exile groups and Radio Free Asia, which is financed by the United States government.

The three deaths — a man and two women — bring the number of Tibetans who have set fire to themselves in western China since March 2011 to at least 25; at least 17 have died.

Free Tibet, an advocacy group, said that an 18-year-old identified as Dorjee set fire to himself on Monday in the Sichuan provincial town of Chara, about 40 miles from the town of Aba, known in Tibetan as Ngaba, where many of the self-immolations have taken place. The group quoted a witness as saying Dorjee walked “in flames to a government office building where he collapsed.”

The Radio Free Asia report said that Rinchen, a 32-year-old widow and mother of three, killed herself by self-immolation on Sunday in front of the Kirti Monastery in in Ngaba. A report by Free Tibet, said Rinchen had four children.