BEIJING (NYTIMES, AFP, REUTERS) - 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 north-eastern China where Liu was being treated for cancer, announced on its website that Liu had died.

He was the first Nobel Peace laureate to die in state custody since Carl von Ossietzky, the German pacifist and foe of Nazism who won the prize in 1935 and died under guard in 1938 after years of maltreatment.

The Chinese government revealed Liu 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.

Liu "will remain a powerful symbol for all who fight for freedom, democracy and a better world", the Nobel Peace Prize committee leader Berit Reiss-Andersen said on Thursday.

Beijing bears a heavy responsibility for Liu's death, added Reiss-Andersen.

"We find it deeply disturbing that Liu Xiaobo was not transferred to a facility where he could receive adequate medical treatment before he became terminally ill," she said. "The Chinese Government bears a heavy responsibility for his premature death," she told Reuters in an emailed statement.

'Hero' of democracy and human rights

Liu's passing triggered expressions of sorrow from around the world.

German Justice Minister Heiko Maas hailed Liu as a "hero". "His non-violent resistance made him a hero in the battle for democracy and human rights. RIP," Maas wrote on Twitter.

Liu was and will remain an inspiration, UN High Commissioner for Human Rights Zeid Ra'ad al Hussein said, expressing his "deep sorrow" at Liu's death.

"The human rights movement in China and across the world has lost a principled champion who devoted his life to defending and promoting human rights, peacefully and consistently, and who was jailed for standing up for his beliefs," Zeid said in a statement.

He said Liu and his wife Liu Xia were a courageous couple and devoted to each other, and he urged Chinese authorities to guarantee her freedom of movement and to let her travel abroad.

Chinese police have kept Liu Xia under house arrest since 2010 and smothering surveillance, preventing her from speaking out about Liu's death and his belated treatment for cancer.

"Can't operate, can't do radiotherapy, can't do chemotherapy," Liu Xia said in a brief video message to a friend when her husband's fatal condition was announced. The message quickly spread online.

Liu's illness had elicited a deluge of sympathy from friends, Chinese rights activists and international groups, who saw him as a fearless advocate of peaceful democratic change.

"The reaction to his illness shows how much he was respected," said Cui Weiping, a former professor of literature in Beijing who knew Liu and now lives in Los Angeles.

"People from all walks of life - friends, strangers, young people - have been outraged to hear that someone with terminal cancer was kept locked up till he died."

Thorn in Beijing's side

The writer's death silences a government critic who had been a thorn in the side of the authorities for decades and became a symbol of Beijing's growing crackdown on dissenting voices.

International human rights groups, Western governments and local activists had urged authorities to free Liu and grant his final wish to be treated abroad. Germany had offered to treat Liu, calling for a "signal of humanity" from China. The United States also said it was willing to take him in.

But officials insisted that Liu was receiving treatment from top Chinese doctors since being granted medical parole following his diagnosis in late May. In response to calls to allow Liu to leave China, the foreign ministry repeatedly said other countries should not interfere in China's internal affairs.

In early July, Liu's Chinese doctors said he was not healthy enough to be sent abroad for treatment, a position that was contradicted by US and German medical experts invited by the hospital to examine Liu's condition. The physicians offered to treat the laureate at hospitals in their home countries.

Human rights groups decried the way the government treated Liu, accusing authorities of manipulating information about his health and refusing to let him leave because they were afraid he would use the freedom to denounce China's one-party Communist regime.

As a gaunt Liu lay in his sickbed, a video was leaked showing the Western doctors praising their Chinese counterparts - a scene that was denounced as "grotesque propaganda" by Human Rights Watch.

The German embassy said the video seemed to show that security organs were "steering the process, not medical experts".

CHARTER 08

Liu was the co-author of a pro-democracy manifesto called Charter 08, which attracted more than 10,000 signatures online before the authorities deleted the document from internet pages and chatrooms.

He was awarded the Nobel Peace Prize in 2010, a year after he was sentenced to 11 years in prison for inciting subversion. Charter '08, issued in 2008, reflected an apparent shift in China at the time towards becoming more open to liberal ideals, said Beijing-based historian and political commentator Zhang Lifan.

The Nobel prize immediately catapulted Liu Xiaobo into an international A-list of those imprisoned for their beliefs, alongside Nelson Mandela, Aung San Suu Kyi and Carl von Ossietzky.

The last in that list may be unfamiliar to some, but to Beijing he's a particularly uncomfortable parallel, writes BBC.

Carl von Ossietzky was a German pacifist who won the 1935 Nobel Peace Prize while incarcerated in a concentration camp. Hitler would not allow a member of the laureate's family to collect the award on his behalf, noted BBC.

Beijing would not let Liu's wife, Liu Xia, collect the Nobel prize on her husband's behalf and instead placed her under house arrest.

Liu Xiaobo was represented at the 2010 award ceremony in Oslo by an empty chair and the comparisons began between 21st Century China and 1930s Germany.

This story is developing.