Accusing each other of various human-rights abuses, China's verbal salvos carried additional venom this year after the well-publicised prisoner-abuse scandals in Guantanamo Bay and Abu Ghraib.
This prompted human-rights watchers to express concern that US actions have undermined its moral authority, and made it easier for authoritarian governments to justify their human-rights abuses.
Summarising China's human-rights record as "poor", the US report, issued on 28 February by the State Department as part of a yearly review on global human rights, accused China of maintaining "tight restrictions on freedom of speech and of the press".
Highlighting the lack of an independent judiciary and the arrest of several dissent writers towards the end of last year, the report said "many who openly expressed dissenting political views were harassed, detained, or imprisoned", and that the government was "quick to suppress religious, political, and social groups that they perceived as threatening to government authority or national stability".
Covering 118 pages, it also reiterated an earlier criticism that China was using "the international war on terror as a pretext for cracking down harshly on suspected Uighur separatists expressing peaceful political dissent and on independent Muslim religious leaders", in the north-western border province of Xinjiang.
In part wary of radical Islamic influence in the region, since 1997 China has been waging an anti-separatism campaign targeting "extremism", "terrorism", and "splittism". Critics, including the State Department report, say that the campaign has not adequately differentiated between those using peaceful forms of protest and those using violence.
Washington has yet to announce whether it will table a resolution against China's record at this month's UN Human Rights Commission meeting in Geneva. Previous years' resolutions have always failed to be passed.
The Tiananmen Square massacre
of 1989 chilled ties with the West
"It is clear that China's human-rights situation needs improving, but China's human rights are an internal issue," Shen Jiru, a political theorist with the Chinese Academy of Social Sciences, said soon after the report's publication.
In part echoing the government line, Shen questioned whether moral values are always transferable and at what point in a society's development individual human rights should be given priority.
"In China, the biggest problem is economic development as there are so many people with little money or education. Do these people's rights come before the rights of dissidents?" Shen asks.
Issuing a formal response on Wednesday, China's Foreign Ministry spokesman said that only the Chinese people have the right to comment on their human rights and that "the Chinese government, sticking to a policy it calls 'putting people above everything else,' has made many efforts toward building a democratic country under the rule of law".
This was followed on Thursday by their own appraisal of US human-rights record.
Its flowery language contrasting with the US State Department's bureaucratic wording, the report said that "the atrocity of US troops abusing Iraqi PoWs exposed the dark side of human-rights performance of the United States", and that "the world people have to probe the human rights record behind the Statue of Liberty in the United States".
China's reaction to Uighur Muslim
demands has sparked concern
Cataloguing a list of apparent failings within America, including high levels of racial discrimination, rising number of homelessness, and curtailment of rights since 9/11, the report questioned whether the US can justifiable pose as "the world's human rights police".
"The 2004 US presidential election reported many problems, including counting errors, machine malfunctions, registration confusion, legal uncertainty, and lack of respect for voters," the report said.
The report also listed a string of abuses carried out during the war in Iraq. Included were the killing of 45 people at a wedding party in May last year, and the shooting of seven civilians on a bus in Ramadi last November.
"The double standards of the US on human rights and its exercise of hegemonism and power politics under the pretext of promoting human rights certainly put itself in an isolated and passive position and beget opposition from all just members of the international community," the report concluded.
US army abuses have come in for
criticism from Chinese officials
Commenting on the two reports, Mickie Spiegel, China researcher at the New York-based Human Rights Watch, said: "Though I believe the US report on China tries to reflect accurately what is happening, American actions (in Iraq) has made it easier for the Chinese to criticise America, and makes it easier for more abusive governments to justify their own actions.
"In terms of the US ability to speak for people's rights (Iraq) makes it very difficult for people to follow America and this worries me."