A debate over whether to keep certain interrogation techniques secret is holding up the release of a long-awaited military manual on the treatment of detainees.

Coming more than two years after photographs surfaced showing U.S. troops beating, intimidating and sexually abusing prisoners at Abu Ghraib in Iraq, the new Army field manual was initially supposed to include a classified section.

In recent days, however, several members of Congress privately cautioned the Pentagon that keeping parts of the manual secret could raise suspicions that the United States was violating international and U.S. laws and rules governing detainee treatment.

Those conversations led defense officials to privately debate which parts — if any — to keep secret, according to several Capitol Hill and senior defense officials. They spoke on the condition of anonymity because the discussions were private and the manual has not yet been made public.

The classified section was planned to provide detailed guidelines on what can and can't be done to detainees — for example, how long they can be forced to sit or stand in certain positions or exactly how hot or cold their holding areas can be kept.

The Pentagon and the Army have been reviewing a draft of the manual for more than a year and were about to release a final version last week when debate over it intensified. The Bush administration is treading carefully on the issue, mindful that detainee treatment has the potential to become a high-profile controversy once again, this time in an election year.

In a private meeting at the Pentagon last week, Sens. John Warner of Virginia and Carl Levin of Michigan, the top Republican and Democrat on the Senate Armed Services Committee, broached the issue of the manual's classified section with Deputy Defense Secretary Gordon England.

Sen. John McCain, R-Ariz., discussed the issue as well at a separate meeting with England.

"I think they're making progress. I think the debate's a healthy thing. It should be examined," Warner said in a brief interview Tuesday.

Officials say arguments are being made both for and against the inclusion of a classified section.

Those who favor including it argue that enemy combatants will be able to train and prepare for specific interrogation techniques and limits if they know exactly what they are.

"You don't want the enemy to know what are the techniques available," said Sen. Lindsey Graham, R-S.C., an Armed Services Committee member who supports keeping part of the manual secret. "Being classified and humane and within the rule of law of armed conflict are not inconsistent."

On the other hand, making part of the handbook a classified secret could prompt questions about whether the U.S. is hiding practices that might be considered torture. Greater transparency, some argue, would dispel suspicion that the military is exploiting loopholes in the laws.

Last year, Congress — led by McCain — passed a measure against the administration's wishes that explicitly banned cruel, inhuman or degrading treatment of prisoners by U.S. troops.

Elisa Massimino, Washington director of Human Rights First, said that if portions of the new manual are classified in the wake of the prisoner abuse scandal, it would send the wrong message to U.S. troops and the world. "It makes you wonder: Has DOD learned nothing from this debacle?" she said.

Several defense officials said the public portions of the new interrogation manual define more clearly the roles and responsibilities of soldiers involved in detainee operations, outline how to report violations, and say the military must adhere to prisoner protections.

The manual, which is to replace a 1994 Army handbook, also broadly explains the responsibilities of military intelligence officers and interrogators versus the duties of military police and others who may be at a detention facility, the officials said.

After the Abu Ghraib scandal there were concerns that soldiers were confused about what they could or couldn't do and were not clear about who was in charge. The new manual is supposed to clear up that confusion.

In April 2004, photographs were released showing Abu Ghraib prisoners being sexually humiliated and forced to assume painful positions. Others showed U.S. dog handlers holding onto barking dogs that were straining at their leashes, inches away from cowering prisoners.

The photos brought a barrage of criticism and triggered about 600 investigations into detainee-related incidents. Since the invasion of Afghanistan in October 2001, 85 military members have been court-martialed, 93 have received nonjudicial punishments, and there have been 81 other administrative actions taken due to prisoner abuse in Iraq and Afghanistan. Of those, 12 courts-martial and 11 criminal convictions involve detainee abuse at Abu Ghraib. One court-martial is pending.

The previous interrogation handbook specified that torture is prohibited by the Geneva Conventions, and listed various mental and physical abuses that are prohibited.

Along with the new manual, the Pentagon is preparing to release a new directive on the treatment of detainees, including requirements for holding, transferring and releasing them. There will also be a third document involving medical treatment of detainees.