U.S. officials rejected the draft report, saying the experts who wrote it made many errors and treated statements from detainees' lawyers as fact. The United States had invited the experts to Guantanamo but would not let them interview detainees, so they refused to go.
The report recommended the United States close Guantanamo Bay and revoke all special interrogation techniques authorized by the Department of Defense. Its experts accused the United States of violating the detainees' rights to a fair trial, freedom of religion and health.
"In their view, the legal regime applied to these detainees seriously undermines the rule of law and a number of fundamental universally recognized human rights, which are the essence of democratic societies," the report said.
The report's findings were based on interviews with former detainees, public documents, media reports, lawyers, and a questionnaire filled out by U.S. officials.
Many of the allegations have been made before, but the document is the first such accounting from the U.N. rapporteurs, who are charged by the U.N. Commission on Human Rights to investigate rights concerns around the world.
The draft was delivered to the United States on Jan. 16, and was first disclosed Sunday by the Los Angeles Times. A final version, which is likely to incorporate U.S. comments, was expected to be released later in the week.
U.S. State Department spokesman Sean McCormack said the United States would not address many of the claims until the final report is released, but defended U.S. practices generally. He focused his remarks on the fact that the experts had refused to go to Guantanamo but wrote the report anyway.
"When people hear these press reports about these outcomes and when they actually view the final report, I would urge them to look at it in the context of the fact that nobody who wrote this report actually went to Guantanamo," McCormack told reporters in Washington. "You shouldn't be writing this kind of report based on assertions by individuals without having ever been there."
The five experts sought invitations from the United States to visit Guantanamo Bay since 2002 and three were offered a visit last year. But they refused in November when they were told they would not be allowed to interview detainees.