WASHINGTON, June 18 (Reuters) - Medical examinations of 11 former terrorism suspects held by U.S. troops found proof of physical and psychological torture resulting in long-term damage, a human rights advocacy group said on Wednesday.

Mistreatment cited by the men included beatings and other physical and sexual abuse, isolation, forced nakedness and being forced into painful stress positions with their hands and feet bound.

"The evaluations provide evidence of violation of criminal laws prohibiting torture and of the commission of war crimes by U.S. personnel," said the report by the Cambridge, Mass.-based Physicians for Human Rights.

The image of the U.S. military has been tarnished by abuses at Abu Ghraib prison in Iraq and criticism over the detention facility at the U.S. Naval base at Guantanamo Bay on Cuba. Rights groups have condemned the U.S. government for allowing harsh interrogation techniques.

Physicians for Human Rights said its report provided the most detailed account available -- supplemented by medical evidence -- of the experience of detainees in U.S. custody who suffered torture at the hands of U.S. personnel.

"Additionally, this report provides further evidence of the role health professionals played in facilitating detainee abuse by being present during torture and ill-treatment ... and failing to stop or document detainee abuse," it said.

The report said seven of the 11 had considered suicide after their abuse.

The report was released a day after a congressional hearing discussed how Pentagon officials had developed interrogation techniques after the Sept. 11 attacks, amid questions over whether there was a systematic government effort to determine the harshest methods.

TORTURE AND ABUSE 'SECOND TO NONE'

Physicians for Human Rights conducted two-day clinical interviews and evaluations of each of the 11 former detainees to document psychological and physical consequences of their treatment while in custody.

Four of the men were arrested in or brought to Afghanistan between late 2001 and early 2003 and were later sent to Guantanamo. They were held for an average of three years before being released without charge.

The other seven were detained in Iraq, most in the notorious Abu Ghraib prison, in 2003 and released without charge later that year or in 2004.

"As a physician with more than 15 years of experience evaluating and caring for torture victims from all over the world, the torture and abuse these men were subjected to in Abu Ghraib and the resulting trauma are second to none," said Allen Keller, one of the medical evaluators for the study.

Keller said he and his colleagues found "clear physical and psychological evidence" of torture and abuse, often causing lasting suffering.

Leonard Rubenstein, president of the advocacy group, said the men, particularly those held in Iraq, described a system of "gratuitous cruelty" by U.S. personnel.

"Another key finding is that the authorized techniques, many of which themselves amount to torture, begat yet additional forms of torture, proving once again that once torture starts it can't be contained," Rubenstein said.

The report gave one example of the case of a man named Amir, who was arrested by U.S. forces in Iraq in August 2003.

Amir said while at Abu Ghraib prison he was placed in a foul-smelling room and forced to lay face down in urine while he was hit and kicked. He was also sodomized with a broomstick and forced to howl like a dog while a soldier urinated on him. After a soldier stepped on his genitals, he fainted.

Amir continues to experience physical and psychological symptoms nearly four years after being released, the report said.

Rubenstein said the report showed the extent of the men's pain and suffering -- now and at the time of their detention.

"The pain from the beatings and stress positions, including suspension, combined with feelings of humiliation and shame was so bad it led seven men to consider suicide despite prohibitions in the Muslim religion," he said. (Editing by David Storey and Vicki Allen)