The Nobel Peace Prize committee is preparing to host this year's award ceremony, amid continuing anger from China government at this year's winner. Chinese dissident Liu Xiaobo - currently jailed in north-east China - will not be in Oslo to get his prize. Nobel committee chairman Thorbjorn Jagland has said the award should not be seen as a statement against China. However, ahead of the ceremony, the UN said it had information that China had detained at least 20 activists. China has waged a wide-ranging campaign to discredit the award in recent weeks. It has sought to prevent anyone travelling from China to Oslo, in Norway, to collect the prize on Mr Liu's behalf. And it launched its own peace prize, the Confucius Peace Prize, handing out the inaugural award on Thursday. 'Not a protest' On the eve of the Nobel ceremony, Mr Jagland said the award was about universal human rights and "honouring people in China". He said: "This is not a protest, it is a signal to China that it would be very important for China's future to combine economic development with political reforms and support for those in China fighting for basic human rights." Mr Jagland said there would be an empty chair for an absent Nobel laureate at the award ceremony on Friday. The empty chair would be "a very strong symbol [that] shows how appropriate this prize was," he said. It will be the first time since 1936 that the award, now worth $1.5m, will not be handed out. UN human rights chief Navi Pillay on Thursday again called for Mr Liu to be released "as soon as possible". The Chinese government has been furious about the award ever since it was announced in August that Liu Xiaobo had won it. Beijing believes that Mr Liu - a veteran of the 1989 Tiananmen Square protests - is a criminal, and insists that giving him a prize is an insult to China's judicial system. At least 18 nations are set to boycott the ceremony. "We hope those countries that have received the invitation can tell right from wrong, uphold justice," Chinese foreign ministry spokeswoman Jiang Yu said. Earlier this week she said those who supported the award were "anti-China clowns". As well as putting Liu Xia, the Nobel laureate's wife, under house arrest, other activists and dissidents have faced pressure from the authorities. Some have been prevented from leaving the country, others have been forced to leave their homes for the next few days, according to the Chinese Human Rights Defenders. One of those to disappear, it said, was Zhang Zuhua, the man who co-wrote Charter 08, a political manifesto that Liu Xiaobo also helped draft. Websites 'blocked' The BBC has been given a letter that shows just how determined the Chinese government has been to persuade foreign diplomats not to attend the Nobel Peace Prize ceremony. It was sent by the Chinese embassy in Norway to the delegation of the European Commission in Oslo. Using forceful language, the letter criticises Liu Xiaobo, saying he had done "everything possible to sabotage China's development and stability". It adds: "We strongly hope that your country... will refrain from attending any activities directed against China." Liu Xiaobo first came to prominence when he took part in the 1989 protests in Beijing's Tiananmen Square. He was sent to prison for nearly two years for his role, and has been a critic of the Chinese government ever since. He was given an 11-year prison sentence in December 2009 for inciting the subversion of state power, a charge which came after Charter 08 was published. The document calls openly for political reforms in China, such as a separation of powers and legislative democracy. Meanwhile, the BBC website appears to have been blocked in China. Users in several parts of the country have reported that they are unable to access the BBC's internet site, while the BBC has noticed a steep drop in traffic from China. It is the first time the BBC's English-language website has been blocked since the Beijing Olympics in 2008. Access to other international news sites such as CNN also appears to be restricted. Source: BBC