Jailed Chinese dissident Liu Xiaobo was awarded the Nobel Peace Prize in a ceremony where he was represented by an empty chair and he dedicated it from prison to the "lost souls" of the 1989 Tiananmen Square crackdown.
China called the award in Oslo a "political farce".
US president Barack Obama, a Peace Prize laureate last year, called for the prompt release of 54-year-old Mr Liu, who was jailed last year for 11 years for subversion.
In Beijing, police stepped up patrols at key points today, including Tiananmen Square, where witnesses say hundreds or thousands were killed when troops crushed reform protests, and Mr Liu's apartment where his wife is believed to be under house arrest. Authorities tightened a clampdown on dissidents.
There were no signs of trouble in Beijing where memories of Tiananmen have faded for many as China has risen as a global economic and political power while guarding the Communist Party's tight hold on society.
Instead of awarding the Nobel medal and citation to Mr Liu, it was simply placed on his chair in the ceremony in Oslo's City Hall as the audience cheered. A large portrait of the laureate, bespectacled and smiling, hung nearby.
Norwegian actress Liv Ullmann read out an address made by Mr Liu, who was closely involved in Tiananmen and more recently helped found the reform group Charter 08, to a court during his trial for subversion in December 2009.
"I, filled with optimism, look forward to the advent of a future, free China," the address said.
"For there is no force that can put an end to the human quest for freedom, and China will in the end become a nation ruled by law, where human rights reign supreme."
"Hatred can rot away at a person's intelligence and conscience. (The) enemy mentality will poison the spirit of a nation, incite cruel mortal struggles, destroy a society's tolerance and humanity, and hinder a nation's progress toward freedom and democracy."
It was the first time that a laureate under detention had not been formally represented since Nazi Germany barred pacifist Carl von Ossietzky from attending in 1935. Several jailed or detained laureates since had been represented by family but China's did not allow anyone near Mr Liu to travel to Oslo.
The thousand guests in the city hall rose to a standing ovation when Norwegian Nobel committee chairman Thorbjoern Jagland called for Mr Liu's release.
"Liu has told his wife that he would like this year's Peace Prize to be dedicated to 'the lost souls from the 4th of June.' It is a pleasure for us to fulfil his wish," Mr Jagland said.
An economically strong China with full civil rights would benefit the world but without them would be in "danger of social and economic crises... with negative consequences for us all," Mr Jagland said.
"We can to a certain degree say that China with its 1.3 billion people is carrying mankind's fate on its shoulders."
China appeared to have blocked Western news websites, including the BBC and CNN, and state media made no mention of the ceremony, aside from a statement condemning the prize.
Mr Liu's fame overseas was lost on many residents in Beijing, where lives of millions have radically changed since the 1989 crackdown on pro-democracy protesters.
"Everything is different now since the revolt of 1989. People's ideas have changed. China has changed," said businesswoman Ma Junpeng. "People like Liu are irrelevant."
With the clampdown forcing dissidents to remain in China, about 150 Liu-supporters living abroad travelled to Oslo to take part in the gala for their colleague and hero.
"Liu is the soul of China. I know that deep down, the people of China don't agree with this regime," said Flavie Zhang, 45, who now lives in France. "I was in tears during the ceremony."
About 40 anti-Liu protesters staged a counter-demonstration in Oslo carrying signs: "Liu is a criminal", "Peace Prize to China" and "No meddling in China's internal affairs".
At one point some anti-Liu protestors shoved rivals carrying "Free Liu Xiaobo" signs, then bashed one of the signs to pieces.
"I feel threatened and understand why many Chinese people feel they cannot come out and express their support," said Mandy Kan, 36, a Hong Kong native who lectures at Oxford University.
Xiu Hua, a researcher who left China in the 1980s, said she regretted the altercation but added, "The Nobel committee totally misunderstands China."
Reuters