International condemnation has followed the sentencing of prominent Chinese dissident Liu Xiaobo.
The top United Nations human rights official said she was deeply concerned.
UN High Commissioner for Human Rights Navi Pillay released a statement Friday saying the conviction and what she called the extremely harsh sentencing marked a severe restriction on freedom of expression in China.
The United States and the European Union also condemned the ruling.
Earlier Friday, Liu was sentenced to 11 years in prison on subversion charges after he called for sweeping political reforms and an end to Communist Party dominance.
Liu was the co-author of an unusually direct appeal for political liberalization in China called Charter 08. He was detained last December, just before its release. Thousands have signed the charter over the past year, even though a news blackout and Internet censorship have left most Chinese unaware it exists.
China has accused foreign diplomats of "meddling" in its own "internal" affairs.
The London-based Amnesty International group also condemned the sentence, saying it was "deeply concerned" for the thousands of other people who have signed Charter 08.
The San Francisco-based Dui Hua Foundation says the sentence was the longest it knew of since the crime of inciting subversion was established in 1997.
Liu's wife says he will appeal the sentence.
More than 300 international writers, including Salman Rushdie, Umberto Eco and Margaret Atwood, have called for his release, saying he should be allowed to express his opinion.
Liu is an outspoken former university professor who has advocated for greater political freedom in China for two decades. He spent nearly two years in detention after the 1989 crackdown on pro-democracy protesters in Beijing's Tiananmen Square.
Some information for this report was provided by AP, AFP and Reuters