The new figure is nearly double the 49 cases of abuse disclosed two weeks ago by senior Pentagon officials - and the number is expected to rise.
It is a blow to the administration's efforts to portray the highly publicised abuse cases at Abu Ghraib prison as isolated incidents.
US commanders have opened 91 investigations into misconduct by US soldiers against detainees and civilians, an army official said, confirming a report on the higher number by The Washington Post.
But the official cautioned that the tally was about two weeks old, and the army's Criminal Investigation Command was still gathering information on the outstanding investigations.
It was likely that the total was higher, the official said, noting that cases were difficult to track because commanders can conduct investigations without reporting them up the chain of command.
Officials expect more cases
The Washington Post photo
Senior army officials on 22 May told reporters that 37 death cases and 16 assault cases have been investigated since August 2002. Of the death cases, only nine were under active investigation.
The latest numbers do not appear to include any new deaths, but rather more assault cases than previously reported and cases of alleged theft by soldiers.
Physical abuse and theft
The Washington Post said they included 18 cases of soldiers accused of stealing jewellery, money or other property from civilians, and 40 cases of assault in which civilians or detainees were kicked or beaten, or weapons were fired to frighten them.
Most cases - 49 - involved incidents outside detention centres.
The assault cases have led to 14
The newspaper cited a senior army official as saying the assault cases led to 14 court martials and seven instances in which non-judicial punishment was meted out.
Only one homicide has resulted in disciplinary action: a soldier was demoted and discharged for shooting a prisoner who was throwing stones at him.
Eight other suspected murders are under active investigation and a ninth has been turned over to the Justice Department because it involved a CIA contract employee.
Meanwhile, an investigation into the role of military intelligence at Abu Ghraib continues under the army's deputy chief of staff for intelligence, Major General George Fay.
Fay is to submit his report to Lieutenant General Ricardo Sanchez, the commander of US forces in Iraq, no later than 15 June, a second army official said.
So far, only seven military police guards have been charged in connection with the abuses at Abu Ghraib which were documented in hundreds of photographs and video clips that showed prisoners being sexually humiliated and physically tormented.
Most of the guards have alleged they were urged by military intelligence interrogators to soften up the prisoners, who were supposed to enjoy Geneva Convention protections against inhumane and degrading treatment.
A key question is whether more aggressive interrogation techniques used on al-Qaida suspects in Afghanistan and at a detention centre in Guantanamo Bay, Cuba, were imported to Iraq.
The New York Times reported over the weekend that interrogation teams were sent from Guantanamo to Iraq and played a central role in training military intelligence interrogators at Abu Ghraib during the period when the abuses occurred.