Chinese police have begun questioning writers, artists and intellectuals who dared to sign a new charter demanding political reforms. It is a move that sets the mood for the year in which the Communist Party will mark the 60th anniversary of its rule.

From across China, reports are emerging of officials and even police calling in some of the 303 people who put their names to Charter 08, a document calling for greater civil rights and an end to the political dominance of the Communist Party.

The co-author, the literary critic Liu Xiaobo, has been in detention since December 8, the day before the bold manifesto was published online.

Another signatory, Xu Youyu, a professor of philosophy at the Chinese Academy of Social Sciences, has written an open letter describing how he was notified by his superiors that the charter was “nonsense” and he should retract his signature. He refused.

Other signatories have been questioned but declined to be identified for fear of reprisals. One source told The Times: “People are being called in and questioned about who organised the manifesto and whether they had signed in person. We hear that the leaders at the top have decided that they cannot tolerate Charter 08.”

The interrogations had, so far, been mostly polite, he said. The aim appeared to be to identify the organisers.

Mr Liu, 53, one of four leading intellectuals who joined the student protesters in Tiananmen Square as they demanded greater democracy in 1989, was detained almost a month ago for his role in putting together the manifesto. His wife, Liu Xia, was allowed to visit him on New Year’s Day at a secret location outside Beijing. A source close to the family said: “She was not allowed to see where she was taken and Liu Xiaobo didn’t know where he was being held. He is being taken care of and is well fed but he undergoes interrogation every day.”

The source said that Mr Liu, who has spent several years either serving a jail sentence or in detention, was in good spirits but was allowed no access to books, television or newspapers. “He could not tell his wife very much, because the police were present throughout their two-hour meeting and lunch together.”

Mr Liu’s lawyer, Mo Shaoping, said that he was being held under a form of house arrest called residential surveillance but legal procedure had been violated because Mr Liu had been removed from his home. Residential surveillance can last for up to six months, and renewal is possible. That means Mr Liu could be held until after the sensitive 20th anniversary of the June 4, 1989, Tiananmen Square protest.

Among the signatories to Charter 08 is the former top party official Bao Tong, who put his name to the document describing himself as “a citizen”. In an essay written from his Beijing home, he wrote: “Would the powers that be please tell 1.3 billion people why freedom is a crime?” Mr Bao was jailed for seven years after the 1989 crackdown and lives under close surveillance.

Charter 08: the demands

— China . . . must divest itself of the authoritarian notion of reliance on an “enlightened overlord” or an “honest official”

— Must “turn toward a system of liberties, democracy, and the rule of law”

— Charter calls for 19 points of change, including rights to freedom of expression and assembly; the separation of powers of the legislative, judicial, and executive branches of government; election of public servants; and a guarantee of human rights

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