Another Tibetan protestor has been killed in China's southwestern Sichuan province after security forces opened fired on thousands of demonstrators.

The death of 20-year-old student called Urgen in Aba prefecture would be at least the third such killing this week.

According to the Free Tibet group, police and troops opened fire when a crowd gathered to protect another man being sought for distributing leaflets in Aba, The BBC reports.

Tibetan rights groups said that incident took place on Thursday when a young man distributed posters in Warma saying the immolations would not stop unless Tibet was free and the exiled Tibetan spiritual leader the Dalai Lama was allowed to return.

Chinese police tried to arrest the young man and then fired when a crowd of Tibetans tried to prevent them from taking him away.

Tibetan rights groups say the immolations and protests are a sign of rising frustration among Tibetans because of growing religious repression and harsh security measures adopted by China.

According to the report, Tibetan areas of Sichuan are now said to be under a security lockdown with roadblocks, checks on all travellers, and Internet and phone services cut. (ANI)