Two Britons released from the US base at Guantanamo Bay have sent an open letter to President Bush detailing the alleged abuse they suffered there.
The US detained Shafiq Rasul for more than two years
Shafiq Rasul and Asif Iqbal, held at the base for more than two years, said they were deliberately humiliated.
Guards used strobe lights, dogs and loud music - particularly from US rapper Eminem - to extract information, they allege.
US military officials at Guantanamo have denied the accusations.
"We have never applied any of those techniques," the Associated Press quoted a spokesman for the US mission at Guantanamo as saying.
Mr Rasul and Mr Iqbal, both from Tipton, West Midlands, said detainees often were forced to go naked as punishment for minor offences, even when female guards were present.
They also said they were forced to squat with their hands chained between their legs for hours during questioning.
"Soldiers told us, 'We can do anything we want'," the
men said in the open letter to Mr Bush and members of the Senate Armed Services Committee.
They said they were driven to falsely confess they were two figures in an August 2000 videotape that also
showed al-Qaeda leader Osama Bin Laden.
The men's lawyer, Barbara Olshansky of the American Centre for Constitutional Rights, said: "They have made clear from the outset that, right from the moment of their arrival, they were subjected to these types of interrogation and intimidation methods.
"It appeared to them that this was the routine and the method of extracting information from people there," she told BBC Radio 4's Today programme.
She said her clients had written to President Bush to "make sure it is clear to the world that what happened to them didn't happen in a vacuum and is very much part of the policy of the American military in handling these various situations around the world."
Ms Olshansky said her organisation is seeking concrete evidence of techniques used at Guantanamo Bay, with a view to "perhaps taking action based on the information that we find".
Her clients had been videotaped and photographed throughout their detention, she said.
Former defence minister Lewis Moonie told Today show that if the men's claims proved true, it "must add strain" to the relationship between the UK and US.
Rights groups seek improved conditions at Guantanamo Bay
Mr Rasul and Mr Iqbal are among five Britons released from Guantanamo whom the British Government freed without charge after determining they were not a security threat.
The latest allegations of abuse at the camp come as the Australian Government says it will investigate claims that one of its citizens was abused while at Guantanamo Bay.
The lawyer for Australian David Hicks said he could not give details of the alleged abuse, but he believed it was authorised by the US military.
Lawyer Stephen Kenny said the alleged mistreatment went beyond the excesses regularly reported at Guantanamo.