Human Rights Watch said three soldiers - two sergeants and a captain who were not identified by name - provided the accounts of abuse, which they said occurred at Forward Operating Base Mercury near Falluja from September 2003 through April 2004.
They alleged that a sergeant broke one prisoner's leg with a metal baseball bat. Others were made to hold 19-litre jugs of water with their arms outstretched, according to the report.
Detainees, known as PUCs or "persons under control', were subjected to stress positions, extremes of hot and cold, sleep deprivation, denied food and water and were piled in human pyramids, the report said.
The abuse was meted out as part of military intelligence interrogations or merely to "relieve stress" of troops, the report said.
The report suggested that abuse
of prisoners was widespread
"Everyone in camp knew if you wanted to work out your frustration you show up at the PUC tent. In a way it was sport," a sergeant is quoted as saying.
"One day (a sergeant) shows up and tells a PUC to grab a pole. He told him to bend over and broke the guys leg with a mini Louisville Slugger, a metal bat," he said.
The soldiers were from the 82nd Airborne Division's 1st battalion 504th parachute regiment.
"The accounts here suggest that the mistreatment of prisoners by the US military is even more widespread than has been acknowledged to date, including among troops belonging to some of the best trained, most decorated and highly respected units in the US Army," the report said.
The report says that in many cases the abuses were specifically ordered by military intelligence before interrogations, and that it was widely known by superior officers both inside and outside of military intelligence.
"The accounts here suggest that the mistreatment of prisoners by the US military is even more widespread than has been acknowledged to date"
Human Rights Watch report
According to the report, the captain made persistent efforts to raise his concern about the abuse with his chain of command but was ignored and told to consider his career.
He said when he made an appointment to meet with Senate staffers, his commanding officer denied him permission to leave his base.
The captain was interviewed several days later by representatives of the army's Criminal Investigations Command and the army inspector general.
Lack of guidance
The soldiers attributed the abuse to lack of guidance on the Geneva Conventions rules on the treatment of prisoners and assumptions that they did not apply.
"Trends were accepted. Leadership failed to provide clear guidance so we just developed it. They wanted intelligence."
As long as no PUCs came up dead it happened," one sergeant was quoted as saying.
"We heard rumors of PUCs dying so we were careful. We kept it to broken arms and legs and shit," he said.