The New York-based group, Human Rights Watch, has said the treatment of inmates at Abu Ghraib prison in Iraq and detainees at Guantanamo Bay has significantly weakened the world's ability to protect human rights.
It said the prison abuse by US forces demanded special attention because of the US's visible posture in the world on questions of international rights and civil justice.
The organisation's executive director, Ken Roth, said that the Bush administration had failed to take responsibility for the events at Abu Ghraib.
The report also highlighted the crisis in the Darfur region of Sudan, which has led to the deaths of 70,000 people and the displacement of 1.6 million others.
The group said that crimes committed in the region could not go unpunished.
