China’s most prominent dissident has been arrested formally after more than six months in detention at a secret location near Beijing on charges that could bring a lengthy prison term.

Liu Xiaobo had been held virtually incommunicado under “residential surveillance”, being allowed only two visits from his wife, since he was taken from his Beijing home on December 8 – a day before publication of a document that he co-authored calling for democracy in China.

State media said: "Liu has been engaged in agitation activities, such as spreading of rumours and defaming of the Government, aimed at subversion of the State and overthrowing the socialism system in recent years." The arrest was made by the Beijing Public Security Bureau yesterday.

It said that Mr Liu, 53, had confessed to the charges. This is the first time the long-time critic of the Government has faced such serious charges. He could be sentenced to a maximum of 15 years, his lawyer Mo Shaoping, said. He told The Times that he would demand an immediate meeting with Mr Liu.

Mr Liu's wife, Liu Xia, told The Times that the police came to her home in western Beijing yesterday morning and handed her a formal document notifying her of the charges against her husband. “They have just been to my home. I am very worried and must speak to our lawyer,” she said.

Mr Liu was a well known and outspoken literary critic in the 1980s but sprang to international fame for his role during the student-led demonstrations centred in Beijing in the spring of 1989.

Mr Liu, along with a famed Taiwanese pop singer and two other intellectuals, joined the students in Tiananmen Square on June 2 in a hunger strike in support of their demand for greater freedom of speech and more democracy and to call for an end to corruption. He was with the students when tanks rolled into the heart of the city on the night of June 3 and 4 and helped to persuade the demonstrators not to make a stand and to leave the square without loss of life. Hundreds were killed elsewhere in the city in that crackdown.

He was detained for nearly two years in Beijing's notorious Qincheng prison, where China’s most prominent political leaders and dissidents have been held in the past few decades, but was not formally charged.

He continued to voice his criticism of the authorities and the Communist Party system. He was sentenced to three years of re-education through labour in the 1990s because of his repeated calls to the Government to reconsider its verdit that the student demonstrations were “counterrevolutionary”.

He was among the 303 initial signatories of Charter 08, a manifesto consciously modelled on the Charter 77 drawn up by Vaclav Havel in the former Czechoslovakia, but is the only one to have been detained. Since his arrest several thousand people have added their names to the charter that demands democracy in China.

Ms Liu told The Times in a recent interview:: “Xiaobo had thought he might be taken in for the anniversary of June 4 but he didn’t think that Charter 08 would cause his arrest.” She issued an appeal last week asking President Obama to raise his case.

Mr Liu's case has drawn intense international criticism, with the European Union and the United States demanding his quick release.

Novelists such as Salman Rushdie and the Italian Umberto Eco, as well as Nobel laureates in literature including the Irish poet Seamus Heaney, have also campaigned for him to be set free.

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