Barack Obama's administration has criticised China over its crackdown on dissidents in a week that has seen the passing of a legal deadline to charge or free the detained artist Ai Weiwei.
Amid ongoing talks in Washington designed to improve relations between the United States and China, Secretary of State Hillary Clinton described Beijing's human-rights record as "deplorable" and said that history is against governments that resist democracy.
"They're worried and they are trying to stop history, which is a fool's errand. They cannot do it. But they're going to hold it off as long as possible," Ms Clinton said in an interview published yesterday.
She raised the issue of human rights, though less stridently, at the start of talks that focused on foreign policy and economic matters. Both countries have tried to stress a generally positive track record in relations between the world's two largest economies. But Mr Obama underscored his support for human rights in talks with senior Chinese officials.
The talks come during an ongoing major security operation by China that has seen lawyers, writers and artists detained amid official concerns over unrest, inspired by violent protests in the Arab world, spreading to the world's most populous nation.
Mr Ai has been held for more than 37 days, the point at which suspects under Chinese law should either be formally charged or released.
There has been no official word about where he is being held or if he has been charged.
"We worry about the impact on our domestic politics and on the politics and the stability in China and the region," Ms Clinton said. "We see reports of people, including public-interest lawyers, writers, artists and others, who are detained or disappeared."
Some have been charged, some released and many are missing, according to rights groups. Mr Ai was detained at Beijing's airport as he prepared to travel to Hong Kong. Under Chinese law, the suspect must be charged or released. If a suspect is charged, they can be held for months before trial while the case is investigated further.
At the talks in Washington, China's top foreign-policy official, Dai Bingguo, said his country had made "historic progress" on human rights and any talks on the issue should be on the basis of "equality and mutual respect". He did not refer to the crackdown.
The Chinese authorities say the detention of Mr Ai was because of economic crimes, a claim disputed by dissidents and rights groups. Artists in Beijing's Songzhuang art district have been contacted by officials and asked if they are friends of Mr Ai.
A group of artists from the community was arrested this year for staging an exhibition – Sensitive Zone – that drew the attention of the authorities.
Wei Rujiu, a lawyer involved in the case, said one of the four, Cheng Li, was sentenced to two years in a labour camp. The three other artists were warned and released.
In one of the pieces, Bury Jasmine, the artist Huang Xiang covered his body in plastic jasmine flowers and was buried, a clear reference to the so-called "jasmine revolution" in the Arab world. A film festival in Songzhuang, one of the best-known in the country, has also been cancelled.
In Hong Kong, graffiti artists have sprayed images of Mr Ai in prominent places around the city – including on the wall of the barracks where the People's Liberation Army has its base in the territory. Two members of the territory's pro-democracy party were arrested and accused of carrying out the spraypaint campaign.
In another sign of the campaign against the country's dissidents, the organisers of the Sydney Writers' Festival said China has banned Liao Yiwu, a government critic and outspoken author who wrote The Corpse Walker, from leaving China for security reasons.