Terror suspects held at the US military base in Guantanamo Bay, Cuba, are being subjected to routine religious humiliation, some detainees claim.
They say interrogators use techniques - including sexual taunts - designed to break down devout Muslims.
A lawyer who helped to compile the accounts, Marc Falkoff, told the BBC there was "systematic" religious abuse.
The Pentagon has declined to comment on the allegations, saying inquiries are under way.
About 540 non-Americans - many of whom were captured during the US-led invasion of Afghanistan in 2001 - are still being detained at the naval base, many without charge.
Some of those who have been released have complained of physical abuse, including beatings.
The latest allegations are contained in newly declassified accounts from prisoners interviews' with lawyers.
Mr Falkoff, a New-York based attorney representing 13 Yemeni prisoners at Guantanamo, told the BBC News website: "The government is trying to use religion to humiliate them."
He said his clients had been forced to wear shorts - meaning they were not properly attired for prayer - and that they reported confiscation of religious items.
Sex taunts
One method of humiliation reportedly includes non-Muslim interrogators throwing the Koran on the ground and stepping on it.
Sexually suggestive techniques violating Muslim taboos about sex and contact with women have also been used, Mr Falkoff said.
One of his clients said a female interrogator wearing a tight T-shirt had asked him: "Why aren't you married? You are a young man and have needs."
Accounting to the account, the detainee felt extremely uncomfortable when she sat within inches of him and said: "Are you going to talk or are we going to do this for six hours."
Another of Mr Falkoff's clients said he had heard of an inmate being smeared with what was purported to be menstrual blood.
Mr Falkoff says he was first tempted to dismiss the account.
But last month he read in the media about a yet-to-be published book by a former army sergeant alleging that a Guantanamo prisoner had had red ink spilled on his face and was told it was menstrual blood.
Threats
According to another declassified account quoted by the Washington Post, one detainee said female interrogators wearing lacy lingerie rubbed themselves on him suggesting they "could have some fun" - until he head-butted one of them.
Mr Falkoff some of his clients have been threatened with rape.
"No-one should be subjected to that kind of treatment. We Americans would not want our POWs to be submitted to it," he said.
The Washington Post quoted Pentagon officials as saying wearing skimpy clothes or engaging in suggestive touching would be inappropriate interrogation techniques.
A US military spokesman told the newspaper it was too early to comment of whether the allegations were credible until another military investigation into abuse allegations had been completed.