China put Liu Xiaobo - one of its most influential dissidents - on trial yesterday for subversion despite strong international protest, sending a chill message to activists daring to question its one-party rule with calls for political reform. The 21/2-hour trial in Beijing attracted global attention. A dozen foreign countries sent embassy staff to the court, but all were barred from attending the trial. Liu, co-author of a manifesto that calls for the rule of law and democracy, will be sentenced on Christmas Day. If convicted, he faces up to 15 years in prison for 'inciting subversion of state power'. The trial at the Beijing No 1 Intermediate People's Court shows an increasingly assertive and confident Beijing that cares little about international criticism, analysts say. Xu Youyu, a retired professor of the Chinese Academy of Social Sciences, said a more assertive and stronger China wanted to show it was not concerned by what Western critics said about it. This contrasts starkly with the situation in the past, when China released one or two dissidents ahead of high-level US visits as a gesture of goodwill. Tiananmen student leader Wang Dan was permitted to go into exile to the US just two months before a state visit by US president Bill Clinton in 1998. 'Now that its power and confidence have grown, [Beijing feels] there isn't much it needs from other people,' Xu said. 'It can do what it wants.' The trial was conducted in a virtually closed court. Liu's wife, Liu Xia , who has not been permitted to see her husband since March, was prevented from attending. Only his brother was allowed to attend the hearing. Liu Xiaoxuan said his brother defended himself rationally in court and denied all charges. 'He said [the content of] his articles that criticised the government was within the freedom of speech permitted' in the constitution, Liu Xiaoxuan said. 'He will bravely accept it if the government decides to jail him. But he said he hopes he will be the last victim to be punished for expressing himself.' The younger Liu added that his brother was in good spirits although he appeared pale. Liu's wife said that she was not optimistic about the verdict and feared her husband, who has already been jailed three times, would face another long sentence. Mo Shaoping , one of Liu's lawyers, said the prosecution had taken the incriminating content of his essays out of context. The atmosphere outside the court was tense, with dozens of police vehicles and about 100 uniformed and plain-clothes police standing guard, witnesses said. Police cordoned off the court to prevent Liu's supporters from getting near the building. Police ordered at least a dozen intellectuals who are signatories to the Charter 08 manifesto to stay home, but scores of supporters still turned up in a show of solidarity. Among them were Ai Weiwei , an artist and co-designer of the iconic Olympic 'Bird's Nest' stadium, and legal scholar and activist Teng Biao . 'If Liu Xiaobo is convicted, we should all face the same charge. We feel that we should share the legal responsibility with him,' Teng told reporters shortly before being detained by police. One man unfurled a banner that read: 'The freedom fighter is innocent. Ten thousand years to democracy, 10,000 years to Liu Xiaobo.' He shouted slogans as police took the banner. Other supporters handed out yellow ribbons and tied them to the crowd control barriers, but police quickly removed the symbols of support. At least five of Liu's supporters were detained. Shijingshan district police confirmed they had detained several people but refused to say what crime they had committed. Overseas websites of human rights groups said dozens of petitioners - people who want to lobby Beijing over their grievances - also stood outside the courthouse during Liu's trial. Embassy staff from a dozen countries, including the United States, Canada and Germany, tried to observe the trial but were turned away. Gregory May, a political officer with the US embassy in Beijing who was barred from the hearing, said outside the court the United States called on China to respect the rights of all its citizens and release Liu. Beijing last week warned Western countries against taking up Liu's case after the US and European Union called for his release. Foreign Ministry spokeswoman Jiang Yu said such calls amounted to interfering in the country's judiciary. In Hong Kong, about 20 protesters marched to the central government's liaison office in support of Liu. Led by Szeto Wah, chairman of the Hong Kong Alliance in Support of Patriotic Democratic Movements of China, they chanted slogans and tied yellow ribbons onto the gate of the building. The protesters also left a letter to the Supreme People's Court calling for Liu's release. Staff of the office quickly removed the letter and the ribbons. Critics say the timing of the verdict was likely planned to coincide with Christmas to avoid attracting the attention of China's Western critics.