“The legal regime applied to these detainees seriously undermines the rule of law and a number of fundamental universally recognised human rights, which are the essence of democratic societies,” the report said.

The UN team calls on the US to revoke all special interrogation techniques authorised by the Defence Department.

Many of these allegations have been made before, but these are the first from a UN panel. The report is scheduled to be released this week, and the US will then give its formal rebuttal. But its retort so far has been that the authors had not visited Guantanamo Bay, and that they took the views of detainees’ lawyers (where there were lawyers) as fact.

This is a weak argument. True, the US had invited the UN team — but denied permission for the interviewing of detainees. The authors rightly objected. “What’s the sense of going to a detention facility and doing fact-finding when you can’t speak to the detainees?” Manfred Nowak, the UN special investigator on torture, said. “It’s just nonsense.”

It is not enough to say, as the US tries to do, that the supervisory role is adequately covered by the International Committee of the Red Cross. The ICRC traditionally refrains from publishing its reports. That is part of the deal under which governments give it access. But where officials’ views on Guantanamo have become known, they have been hostile.

The US may believe that it is on stronger ground in asserting that it is not obliged to follow the Geneva Conventions because Guantanamo is outside US territory and it does not deem the detainees to be prisoners of war. US officials held to that position yesterday.

Sean McCormack, a State Department spokesman, said that medical treatment did not violate standard practice. He said: “The doctors down there comply with accepted international practice . . . when there are those individuals who seek to do harm to themselves by going on hunger strike.”

Stubbornness will take the Administration a long way. Already this year it has proposed to take away retrospectively the right of detainees to challenge the legality of their detention — going further than Congress had done. But the Supreme Court has objected, provoking a tussle about the extent of presidential powers in “wartime”.

Lawyers for the “easiest” cases of wrongful detention are attracting international attention and may be making headway. US news organisations are having some success in prising out detainees’ names and nationalities.

The dispute over the “extraordinary rendition” of suspects — seizing them in foreign countries and sending them on for interrogation — is still raw in Europe. That has raised questions about the fate of those who have been tortured, and so cannot be tried before any court. Will they be “legal ghosts” for ever, unable to be tried or released? Above all, the passing of time increases the pressure on the US. As it brings more of its troops home from Iraq, it will be called on more loudly to say whether it also plans to close Guantanamo.

BY THE NUMBERS

2002 starts holding detainees

760 detainees since 2002

500 there at present

180 released

76 sent to custody in countries other than US

10 charged

35 nationalities

4 hunger strikes, US says