Human rights lawyer Tom Wilner, who represents the 11 Kuwaitis locked up as foreign terrorism suspects at the US naval base in Guantanamo Bay, Cuba, described the abuses on Monday in notes after meeting the men last month.
The notes - declassified by the US government - detailed conversations with six of the men, and said the other five recounted similar treatment.
Major Michael Shavers, a Pentagon spokesman, would not offer a point-by-point rebuttal of the allegations, but said: "It is important to note that al-Qaida training manuals emphasise the tactic of making false abuse allegations."
The worst of the abuse, which Wilner labelled as torture, took place at the hands of US forces at detention facilities in Afghanistan and Pakistan before the men were taken to Guantanamo, first used to detain terrorism suspects in January 2002, he said.
Detainees were held in inhuman
conditions, the lawyer said
"All of them were hung from their wrists and beaten, sometimes beaten with chains. At least one was hung upside [down] from his ankles and beaten. They were all beaten, they said, until they would pass out," Wilner said.
"They were stripped naked and kept naked for extended periods of time. They were taunted while naked by female guards.
"At least one of them was sodomised. At least two of them were subjected to electric shocks while hanging from their wrists," Wilner said, adding the shocks were applied using metal paddles placed under the men's arms.
Wilner said the Kuwaitis were chained in painful positions for such long periods of time that they would urinate and defecate on themselves.
"In the original prisons in Pakistan and Afghanistan and at Guantanamo, the most disturbing thing to most of them was religious humiliation. They were mocked for being Muslims,"
"Both there and at Guantanamo, their Qurans were taken, thrown on the floor, stepped on and thrown in the toilets. Their body hair and head hair would be shaved, and crosses would be shaved into it," Wilner added.
"I think that Guantanamo is a stain on the reputation of the United States, a stain on the honour of our nation"
Human rights lawyer
The men said they made "false confessions" of being part of the Taliban or al-Qaida to stop the torture, according to Wilner. He said one prisoner "specifically said to me, 'Look, when this is happening, you tell them what they want to hear to make them stop'".
The abuse was milder at Guantanamo, although several were "very badly beaten up" there and placed in painful stress positions, and at least one was bent over a table and threatened with sodomy, the lawyer said.
Pentagon spokesman Shavers said US policy "condemns and prohibits torture" and that "credible allegations" of illegal conduct by US personnel were taken seriously and investigated.
The United States currently holds about 545 foreign citizens at Guantanamo. Nearly all are being held without charge and some have been imprisoned there for more than three years.
The US has designated them "enemy combatants" and denied them prisoner of war status, which confers certain rights under international law.
Washington has faced international criticism for its treatment of the Guantanamo prisoners. FBI memos made public recently accused Pentagon interrogators of using "torture techniques".
"I think that Guantanamo is a stain on the reputation of the United States, a stain on the honour of our nation," Wilner said.