Beijing: Liu Xiaobo, the renegade Chinese intellectual who kept vigil on Tiananmen Square in 1989 to protect protesters from encroaching soldiers, promoted a pro-democracy charter that brought him an 11-year prison sentence and was awarded the Nobel Peace Prize of 2010 while locked away, died Thursday. He was 61.

The bureau of justice of Shenyang, the city in northeastern China where Liu was being treated for cancer, announced on its website that Liu had died.

Why are the rulers of a rich and powerful China so worried about one individual?Liu Xiaobo speaks during an interview in 2008 before his detention in Beijing. Credit:AP

The Chinese government revealed he had liver cancer in late June only after it was virtually beyond treatment. Officially, Liu gained medical parole. But even as he faced death, he was kept silenced and under guard in a hospital, still a captive of the authoritarian controls that he had fought for decades.

The police have kept his wife, Liu Xia, under house arrest and smothering surveillance, preventing her from speaking out about Liu's death and his belated treatment for cancer.