Feb. 16 (Bloomberg) -- The U.S. should close its anti- terrorism prison in Guantanamo Bay, Cuba, immediately and try all of the detainees or release them, the United Nations said today in a report. The Bush administration rejected the idea.

Holding suspected terrorists at the military camp ``amounts to arbitrary detention,'' the report said. It added that the executive branch of the U.S. is acting as judge, prosecutor and defense counsel for the prisoners ``in violation of various guarantees of the right to a fair trial.''

The report summarizes findings by five UN human rights investigators who spent six months interviewing former detainees. Their work is also based on information provided by the U.S. and by defense lawyers for some of the detainees. The investigators decided not to visit the prison because the U.S. wouldn't allow private interviews.

The report's release comes as the U.S. is under increasing international pressure to shut Guantanamo. German Chancellor Angela Merkel raised the issue with President George W. Bush last month in Washington. The Defense Department argues that the Guantanamo prisoners are enemy combatants not subject to the UN's human rights mandate, and are being held to prevent further terrorist attacks.

Annan Seeks Closure

UN Secretary-General Kofi Annan said while he didn't agree with everything in the study, the authors' basic conclusion was sound. ``Sooner or later there will be a need to close Guantanamo,'' he told reporters in New York. ``Hopefully, as soon as possible.''

There are now about 500 detainees at Guantanamo, some of whom were captured when the U.S. ousted Afghanistan's Taliban regime following the Sept. 11, 2001, attacks. Many have been held for more than three years without charge.

`These are dangerous terrorists that we are talking about,'' White House spokesman Scott McClellan said today in Washington.

McClellan said the International Committee of the Red Cross has ``full access'' to the Guantanamo prisoners and that the U.S. military treats them humanely.

The Pentagon had freed 187 detainees as of Feb. 9 and handed over 80 others to governments including Afghanistan, France, Britain, Russia, Pakistan and Spain. An administrative review board makes an annual assessment of the detainees for possible release or transfer.

The U.S. Army Corps of Engineers is preparing to renovate an unused prison near Kabul, Afghanistan, to hold about 100 Afghan nationals now detained at Guantanamo. The Afghans would be transferred to Afghanistan's custody for possible prosecution, the Corps said last month.

Hunger Strike

About a fifth of those still jailed in Guantanamo mounted a hunger strike beginning in late December in an attempt to gain their freedom. The military has force-fed some of the protesters after determining they wanted to commit suicide to highlight their indefinite confinement, the New York Times reported.

The UN investigators took issue with procedures that might be used at the camp. The U.S. is attempting to redefine the word ``torture'' to permit certain practices by interrogators barred under the ``internationally accepted'' definition of the word, they said.

Prisoners may be exposed to extreme temperatures and deprived of light and sound, be put in isolation, or have their sleep cycles reversed from night to day, the investigators said.

``The interrogation techniques authorized by the Department of Defense, particularly if used simultaneously, amount to degrading treatment,'' the UN team said in their report. ``If in individual cases, which were described in interviews, the victim experienced severe pain or suffering, these acts amounted to torture.''

Information in Doubt

McClellan suggested that the information gathered by the UN researchers might not be trustworthy. ``Al-Qaeda detainees are trained in trying to disseminate false allegations,'' he said.

In November, the UN's human rights officials declined an invitation from the U.S. to visit the prison on Dec. 6, saying the Pentagon wouldn't let them conduct private interviews with the prisoners.

In October the Pentagon had invited the officials with the stipulation that they would not be allowed the private access. Saying that private meetings with the prisoners were a ``non- negotiable'' requirement for the visit, the UN reiterated its request. When no response from the U.S. was received, the UN canceled the trip, UN spokesman Jose Diaz said at the time.

U.K. Case

The torture accusations were taken up by a senior British judge today in a case involving three U.K. residents.

Justice Andrew Collins authorized the individuals, who are detained at Guantanamo and say they are being tortured, to bring a legal action that would force the U.K. government to demand their release.

``Unfortunately it appears that the Americans have a somewhat different view as to what constitutes torture,'' Justice Collins told the High Court in London. The U.S.'s stance ``doesn't appear to coincide with most civilized nations,'' he said.

The U.S. government is also coming under scrutiny this week for its treatment of prisoners in Iraq. Photographs broadcast by an Australian television network showing abuse of Iraqis at Abu Ghraib prison are evidence of ``disgusting'' conduct and may foment violence in the region, a U.S. State Department official said yesterday.

The unreleased photos were from a batch shown around the world in 2004, prompting an international outcry and U.S. congressional hearings.

To contact the reporter on this story: Judy Mathewson in Washington at jmathewson@bloomberg.net

Last Updated: February 16, 2006 18:43 EST