The legal bureau of Shenyang, where Liu was treated at First Hospital of China Medical University, announced his passing. The hospital in Shenyang, China, that has been treating Liu for advanced liver cancer said Wednesday he was in life-threatening condition from multiple organ failure.
Hu Jia, a fellow dissident who counts Liu as a close friend, said the scuffle over his final days proved some of what Liu had been saying all along: that the ruling Communist Party could be "coldblooded and cruel". Beijing had described his Nobel Peace Prize as a western conspiracy when it was given in 2010, and this led to strained relationship between China and Norway for several years. As many as 10,000 people were arrested during and after the protests.
Rights groups said the focus now was to ensure that Mr Liu's wife Liu Xia, who has been held under house detention since her husband won the Nobel Prize, and his brother Liu Hui are allowed to leave China.
Ms Reiss-Andersen also paid tribute, saying: "Liu Xiaobo received the Nobel Peace Prize for 2010 for his efforts to implement the fundamental human rights secured in global instruments as well as in the constitution of the People's Republic of China".
Liu, a former professor, had helped negotiate with the military for the safe passage of students during the 1989 Tiananmen Square protest.
In 1989, Liu, then a visiting scholar at Columbia University, returned to Beijing to participate in the 1989 democracy movement in China and started a hunger strike at Tiananmen Square with other activists.
In recent days, supporters and foreign governments urged China to allow him to be treated for cancer overseas, but Chinese authorities insisted he was receiving the best care possible.
His death was reported in state media in China.
"What happened to Liu Xiaobo tells the whole world about the human rights situation in China", said pro-democracy lawmaker Leung Kwok-hung. Waiting just before his death, Geremie R. Barme, an Australian Sinologist and a close friend of Liu said, "Xiaobo was wedded both psychically and physically to China and its fate". He says a visit Liu made one day to the Metropolitan Museum of Art in NY led to a sort of revelation. Yet for those of us who followed his extraordinarily important and courageous work over the decades, there is a great sense of emptiness and sadness-not so much sadness for Liu himself, who is now free of persecution, but sadness for China's backward march and sadness for the timidity of world leaders at the brutalization of one of the great men of modern times.
He is the first Nobel Peace Prize laureate to die in state custody since 1938, CBS News reports.
Liu, a Nobel Peace Prize laureate, was a lecturer, writer and literary critic.
After the doctors' Sunday statement, China released short videos of their visit, apparently taken without their knowledge, in which the German doctor appeared to praise the care Liu had received from the Chinese doctors.