The Chinese government "bears a heavy responsibility" for the premature death of jailed Nobel Peace Prize laureate Liu Xiaobo, the leader of the Norwegian Nobel Committee that awards the prize said Thursday, after iconic human right defender and democracy advocate lost his battle with cancer.

Berit Reiss-Andersen said in a statement that saying the committee received the news of the death of Liu, who received the Nobel Peace Prize for 2010 for championing human rights in China, with "regret and great sadness."

"The Chinese Government bears a heavy responsibility for his premature death," Reiss-Andersen said.

Liu, a prominent intellectual who was a leading figure in the Chinese democracy movement for almost 30 years, died in a Chinese hospital earlier Thursday after being diagnosed with late-stage liver cancer.

In the last days of his life, Reiss-Andersen recalled, China refused to allow him to go abroad for medical treatment abroad in accordance with his own wishes and the recommendations of the German and American doctors who were allowed to visit him. 

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"While the whole world watched, China chose instead to maintain the isolation of its prisoner," she said.

She also called it "deeply disturbing" that Liu had not been transferred to a facility where he could receive adequate medical treatment "before he became terminally ill."

Liu is perhaps best known as one of the major contributors to Charter 08, the manifesto that pointed out China's obligations to secure fundamental human rights for its citizens.

Reiss-Andersen said that by awarding him the prize, the Norwegian Nobel Committee "wanted to underscore the fundamental connection between developing democracy and creating and securing peace" and to recognize his "non-violent resistance against the oppressive actions of the Communist regime in China."

Liu was not able to attend the award ceremony in Oslo in 2010 as by then he had already been sentenced to 11 years' imprisonment after being convicted of subversion.

"In our view he had not committed any criminal act, but merely exercised his citizen's rights. His trial and imprisonment were unjust," the Nobel committee's chairwoman said.

Liu's absence from the Nobel Peace Prize award ceremony was marked by an empty chair.

"We now have to come to terms with the fact that his chair will forever remain empty. At the same time it is our deep conviction that Liu Xiaobo will remain a powerful symbol for all who fight for freedom, democracy and a better world," Reiss-Andersen said.

"He was truly a prisoner of conscience and he paid the highest possible price for his relentless struggle."

In New York, Human Rights Watch denounced the Chinese government's treatment of Liu, noting that the last Nobel Peace laureate who died in state custody was in 1938, when pacifist Carl von Ossietzky died of tuberculosis under guard in a hospital in Nazi Germany.

"The Chinese government's arrogance, cruelty, and callousness are shocking -- but Liu's struggle for a rights-respecting, democratic China will live on," Sophie Richardson, China director at Human Rights Watch, said in a statement.

Salil Shetty, secretary general of Amnesty International, grieved the loss of Liu, who he called "a man of fierce intellect, principle, wit and above all humanity."

"Despite enduring years of persecution, suppression and imprisonment, Liu Xiaobo continued to fight for his convictions," Shetty said.