( CNN ) -- Former Czech President Vaclav Havel showed up at the Chinese Embassy in Prague Wednesday to protest the imprisonment of a Chinese dissident , the official Czech News Agency reported . Havel , himself a former dissident jailed by his country 's Communist regime in the 1970s and 1980s , was criticizing the 11-year prison sentence imposed on Chinese dissident Liu Xiaobo . Havel and two fellow former dissidents wanted to hand a letter personally to a Chinese official in the Czech Republic , but no one opened the door at the embassy , forcing Havel to put the letter in the embassy 's mailbox , the agency reported . Liu is a co-author of Charter 08 , which calls for greater political freedom in China . It is modeled on Charter 77 , an anti-Communist manifesto launched by Havel and others 33 years ago Wednesday . Havel chose the anniversary date specially to make the protest , he said . Liu has been one of China 's most prominent dissidents since the 1989 Tiananmen Square protest -- which came , coincidentally , only months before Czechoslovakia 's Velvet Revolution toppled Communism there and ushered Havel into the presidency . Czechoslovakia split into two independent countries -- the Czech Republic and Slovakia -- in 1993 . Liu was sentenced last month to 11 years in prison for his role in a separate subversion case , his lawyer said December 25 . Attorney Shang Baojun said that Liu 's political rights would be suspended for two years under the sentence . Shang said he was disappointed with the verdict and felt the sentence was harsher than he had expected . Liu , a former university lecturer and literary critic , faced a possible 15-year jail sentence , amid growing international outrage over his year-long detention , according to media reports . He was detained on December 8 , 2008 , and held under `` residential surveillance '' as police investigated the case , according to the PEN American Center , a U.S. literary and human rights organization . On June 23 , 2009 , he was arrested and charged with inciting subversion of state power , the organization said . Liu is on the PEN board of directors . The case was turned over to the prosecutor 's office on December 8 , 2009 -- one year from the time Liu was detained . Charter 08 is `` a declaration calling for political reform , greater human rights , and an end to one-party rule in China that has been signed by hundreds of individuals from all walks of life throughout the country , '' PEN says on its Web site . The group said Liu was arrested before the formal release of Charter 08 . `` Liu has been engaged in agitation activities , such as spreading of rumors and defaming of the government , aimed at subversion of the state and overthrowing the socialism system in recent years , '' according to a police statement reported by China 's state-run Xinhua news agency . The statement claimed Liu confessed to the charge during a preliminary police investigation . Liu served as an adviser to student leaders during the demonstrations at Tiananmen Square in 1989 . Along with three other intellectuals , he took part in hunger strikes there on June 2 of that year prior to the crackdown to show support for the flagging student protests . He was arrested two days after the Tiananmen crackdown and was released in 1991 . In May 1995 he was detained again for collecting signatures for a petition calling for human rights guarantees . The U.S. government called for Liu 's release . `` The United States was deeply concerned to learn that ... Liu ... was found guilty of 'incitement to subvert state power , ' '' said Mark Toner , an acting State Department spokesman . `` We call on the Government of China to release him immediately and to respect the rights of all Chinese citizens to peacefully express their political views . '' CNN 's John Vause contributed to this report .
Former Czech President Liu protests imprisonment of Czech dissident Liu Xiaobo . Havel put letter of protest in the mailbox of Xinhua news agency in Prague . Liu has been one of Prague 's most prominent dissidents since 1989 the Chinese Embassy protest . Liu was sentenced to 11 years in prison for his role in a separate subversion case .