A popular Tibetan singer named Amchok Phuljung was released late yesterday evening after serving more than four years in prison for singing songs in praise of the exiled Tibetan leaders including the Tibetan spiritual leader His Holiness the Dalai Lama in Marthang (Ch: Hongyuan) County in Ngaba (Ch: Aba) Tibetan and Qiang Autonomous Prefecture, Sichuan Province, in the Tibetan province of Amdo.