WASHINGTON, May 25: The United States, accused by Amnesty International of committing serious human rights violations, has said that the group failed in its obligations when it did not help Iraqi prosecutors prepare their case against Saddam Hussein.

In a report released on Tuesday, Amnesty International claimed that the US government outsourced anti-terror duties to private contractors because they cannot be held accountable for misdeeds, such as torturing prisoners.

The group urged the US to tighten the rules governing private contractors so that they can also be held accountable for human rights violations they commit.

State Department spokesman Sean McCormack said charges of mistreatment of detainees at Guantanamo Bay and other US facilities were incorrect, adding that the US desires to close the prison camp in Cuba as soon as it is practical.

Mr McCormack also rejected Amnesty charges that the indefinite detention of terrorism suspects at Guantanamo amounted to cruel and inhuman treatment, or that torture was practiced there.

He said the US hopes to eventually close the Guantanamo facility, but regretted critics provide no answers about what should be done with the detainees.

The spokesman said the US was bearing a burden for others in detaining would-be terrorists and was willing to repatriate those who can be sent home. The US, he said, had also sought guarantees from various countries that those freed will not be mistreated or be allowed to return to terror activity.

Nearly 500 detainees, most of them suspected Al Qaeda and Taliban members taken prisoner during the invasion of Afghanistan, remain at the Cuba facility.