Governments around the world betrayed their commitment to human rights in 2004, Amnesty International says.
The US is accused of damaging human rights across the world
In a 300-page annual report, the group accused the US government of damaging human rights with its attitude to torture and treatment of detainees.
This granted "a licence to others to commit abuse with impunity", the human rights advocates said.
In Washington, a White House spokesman branded the allegations "ridiculous and unsupported by the facts."
"The United States is leading the way when it comes to
protecting human rights and promoting human dignity. We have
liberated 50 million people in Iraq and Afghanistan, we have
worked to advance freedom and democracy in the world," said
The report also criticised the world as a whole for failing to act over crises, notably in Sudan's Darfur region.
Afghanistan was slipping into a "downward spiral of lawlessness and instability", it added.
Published on Wednesday, the report accused governments of adhering stubbornly to "politically convenient" but inefficient tactics to address terrorism in 2004, despite what Amnesty saw as a lack of success.
The televised beheading of captives in Iraq, the bombing of commuter trains in Madrid and the siege at a school in Beslan in Russia showed that "four years after 9/11, the promise to make the world a safer place remains hollow", secretary general Irene Khan said.
In Iraq some of the violence could be blamed on armed groups but the report also blamed US-led coalition forces for "unlawful killings, torture and other violations".
"Torture and ill-treatment by US-led forces were widely reported," it added.
The report also highlighted the London-based organisation's concerns about:
- A lack of accountability for human rights violations in Haiti and in the Democratic Republic of Congo
- Reported abuses by Russian forces in Chechnya
- New levels of brutality against civilians by armed groups in places like Iraq
- Slow progress in achieving the Millennium Development goals
- Indifference to violence against women
- Lack of a full independent investigation into abuses against detainees in US custody in Iraq, Afghanistan and Guantanamo Bay.
In its wide-ranging review of 131 countries and five world regions, Amnesty International said the US government's selective disregard for international law and reported abuses of detainees was sending a "permissive signal to abusive governments".
"The US, as the unrivalled political, military and economic hyper-power, sets the tone for governmental behaviour worldwide," she said.
"When the most powerful country in the world thumbs its nose at the rule of law and human rights, it grants a licence to others to commit abuse with impunity."
The administration was seeking "to dilute the absolute ban on torture", Ms Khan added.
Rejecting Amnesty's charges, Mr McClellan said the US investigated all allegations of abuse.
"We hold people accountable when there's abuse. We take steps to prevent it from happening again. And we do so in a very public way for the world to see that we lead by example and that we do have values that we hold very dearly and believe in," he told reporters in Washington.
Ms Khan also condemned the United Nations Commission on Human Rights for failing to stand up for those supposedly in its care.
"The UN Commission of Human Rights has become a forum for horse-trading on human rights," she said.
"Last year the commission dropped Iraq from scrutiny, could not agree on action on Chechnya, Nepal or Zimbabwe and was silent on Guantanamo Bay."