More than 20 Tibetan students were injured during a protest in the Qinghai province of China over a controversial book as four more self-immolations were reported taking the toll to over 20 in November.
The four self-immolations, according to overseas rights groups, occurred in Gansu, Sichuan and Qinghai provinces on Sunday and Monday.
At least three among them who self-immolated have died, rights groups said.
Teenage nun Sangay Dolmas died in Qinghai on Sunday. Kunchok Tsering, 18, and Gonpo Tearing, 24, died in Gansu on Monday.
More than 80 Tibetans have set themselves alight since 2011 in what activists say are protests against Beijing's hardline and repressive rule. Most of the cases have occurred in Tibetan areas outside Tibet.
The spate of protests suicides began in the run-up to the 18th National Congress of the Communist Party of China (CPC), which named Xi Jinping as the Party's new general secretary earlier in November.