A U.N. inquiry has called for the immediate closure of America’s Guantanamo Bay detention center and the prosecution of officers and politicians “up to the highest level” who are accused of torturing detainees.

The U.N. Human Rights Commission report, due to be published this week, concludes that Washington should put the 520 detainees on trial or release them.

It calls for America to halt all “practices amounting to torture,” including the force-feeding of inmates who go on hunger strike.

The report wants the Bush administration to ensure that all allegations of torture are investigated by American criminal courts, and that “all perpetrators up to the highest level of military and political command are brought to justice.”

It does not specify who it means by “political command” but logically this would include President Bush.

The demands are contained in the final report of the commission’s working group on arbitrary detention, which will be presented at its Geneva headquarters in the next few days. A copy of the report has been obtained exclusively by the Daily Telegraph.

The report is bound to intensify the already strained relations between America and the United Nations over the Iraq war. Washington officials yesterday denounced it as “a hatchet job” when informed of the contents by this newspaper.

“This shows precisely what is wrong with the United Nations today,” a senior official said. “These people are supposed to be undertaking a serious investigation of the facts relating to Guantanamo.

“Instead, they deliver a report with a bunch of old allegations from lawyers representing released detainees that are so generalized that you cannot even tell what they are talking about. When the U.N. produces an unprofessional hatchet job like this it discredits the whole organization.”

The Bush administration has repeatedly called for the U.N.’s wholesale reform, and the report is likely to lead to demands from Congress for a freeze on Washington’s annual donations.

The authors question the right of America to classify the detainees as “enemy combatants” and argue that the “war on terror” is no justification for holding them indefinitely without charge.

The report is also deeply critical of America over recent disclosures that some of the detainees have been subjected to force feeding when they have gone on hunger strike. The authors argue that force feeding is akin to torture, and demands that “the authorities in Guantanamo Bay do not force feed any detainee who is capable of forming a rational judgment and is aware of the consequences of refusing food.”