The accounts, in interviews with The New York Times, come as mental health professionals are debating whether psychiatrists and psychologists at the prison camp have violated professional ethics codes. The Pentagon and mental health professionals have been examining the ethical issues involved.

The former interrogators said the military doctors' role was to advise them and their fellow interrogators on ways of increasing psychological duress on detainees, sometimes by exploiting their fears, in the hopes of making them more cooperative and willing to provide information. In one example, interrogators were told that a detainee's medical files showed he had a severe phobia of the dark and suggested ways in which that could be manipulated to induce him to cooperate.

In addition, the authors of an article published by The New England Journal of Medicine this week said their interviews with doctors who helped devise and supervise the interrogation regimen at Guantánamo showed that the program was explicitly designed to increase fear and distress among detainees as a means to obtaining intelligence.

The accounts shed light on how interrogations were conducted and raise new questions about the boundaries of medical ethics in the nation's fight against terrorism.

Bryan Whitman, a senior Pentagon spokesman, declined to address the specifics in the accounts. But he suggested that the doctors advising interrogators were not covered by ethics strictures because they were not treating patients but rather were acting as behavioral scientists.

He said that while some health care personnel are responsible for "humane treatment of detainees," some medical professionals "may have other roles," like serving as behavioral scientists assessing the character of interrogation subjects.

The military refused to give The Times permission to interview medical personnel at the isolated Guantánamo camp about their practices, and the medical journal, in an article that criticized the program, did not name the officials interviewed by its authors. The handful of former interrogators who spoke to The Times about the practices at Guantánamo spoke on condition of anonymity; some said they had welcomed the doctors' help.

Pentagon officials said in interviews that the practices at Guantánamo violated no ethics guidelines, and they disputed the conclusions of the medical journal's article, which was posted on the journal's Web site on Wednesday.

Several ethics experts outside the military said there were serious questions involving the conduct of the doctors, especially those in units known as Behavioral Science Consultation Teams, BSCT, colloquially referred to as "biscuit" teams, which advise interrogators.

"Their purpose was to help us break them," one former interrogator told The Times earlier this year.

The interrogator said in a more recent interview that a biscuit team doctor, having read the medical file of a detainee, suggested that the inmate's longing for his mother could be exploited to persuade him to cooperate.

Dr. Stephen Xenakis, a psychiatrist and former Army brigadier general in the medical corps, said in an interview that "this behavior is not consistent with our medical responsibility or any of the codes that guide our conduct as doctors."

The use of psychologists and psychiatrists in interrogations prompted the Pentagon to issue a policy statement last week that officials said was supposed to ensure that doctors did not participate in unethical behavior.

While the American Psychiatric Association has guidelines that specifically prohibit the kinds of behaviors described by the former interrogators for their members who are medical doctors, the rules for psychologists are less clear.

Dr. Spencer Eth, a professor of psychiatry at New York Medical College and chairman of the ethics committee of the American Psychiatric Association, said in an interview that there was no way that psychiatrists at Guantánamo could ethically counsel interrogators on ways to increase distress on detainees.

But in a statement issued in December, the American Psychological Association said the issue of involvement of its members in "national security endeavors" was new.

Dr. Stephen Behnke, who heads the group's ethics division, said in an interview this week that a committee of 10 members, including some from the military, was meeting in Washington this weekend to discuss the issue.

Dr. Behnke emphasized that the codes did not necessarily allow participation by psychologists in such roles, but rather that the issue had not been dealt with directly before.

"A question has arisen that we in the profession have to address and that is where we are now: is it ethical or is it not ethical?" he said.

Dr. William Winkenwerder Jr., assistant secretary of defense for health matters, said the new Pentagon guidelines made clear that doctors might not engage in unethical conduct. But in a briefing for reporters last week, he declined to say whether the guidelines would prohibit some of the activities described by former interrogators and others. He said the medical personnel "were not driving the interrogations" but were there as consultants.

The guidelines include prohibitions against doctors' participating in abusive treatment, but they all make an exception for "lawful" interrogations. As the military maintains that its interrogations are lawful and that prisoners at Guantánamo are not covered by the Geneva Conventions, those provisions would seem to allow the behavior described by interrogators and the medical journal. The article in the medical journal, by two researchers who interviewed doctors who worked on the biscuit program, says, "Since late 2002, psychiatrists and psychologists have been part of a strategy that employs extreme stress, combined with behavior-shaping rewards, to extract actionable intelligence."

The article was written by Dr. M. Gregg Bloche, who teaches at Georgetown University Law School and is a fellow at the Brookings Institution, and Jonathan H. Marks, a British lawyer who is a fellow in bioethics at Georgetown and Johns Hopkins Universities.

Dr. Bloche said in an interview that the use of health professionals in devising abusive interrogation strategies was unethical and led to their involvement in violations of international law. Dr. Winkenwerder said on Thursday that the article was "an outrageous distortion" of the medical situation at Guantánamo, according to Reuters news agency.

The article also challenges assertions of military authorities that they have generally maintained the confidentiality of medical records.

The Winkenwerder guidelines make it clear that detainees should have no expectation of privacy, but that medical records may be shared with people who are not in a medical provider relationship with the detainee only under strict circumstances.

Dr. Bloche said such an assertion was contrary to what he had discovered in his research. It is also in conflict with accounts of former interrogators who previously told The Times that they were free to examine any detainee's medical files. After April 2003, when Defense Secretary Donald H. Rumsfeld tightened rules on detainee treatment, one interrogator said the records had to be obtained through biscuit team doctors who always obliged.

The former interrogator said the biscuit team doctors usually observed interrogations from behind a one-way mirror, but sometimes were also in the room with the detainee and interrogator.