Sergeant Javal Davis, 27, admitted to stomping on the fingers and toes of a group of seven bound and hooded inmates during an episode of late-night abuse in November 2003. Other guards then undressed the prisoners and stacked them into a naked human pyramid.

In a separate case also heard at the military base in Fort Hood, Texas, military intelligence soldier Specialist Roman Krol pleaded guilty to pouring water on Iraqi prisoners as they crawled naked on the floor and throwing a football at detainees.

Sergeant Davis is one of seven reservists from the US Army’s 372nd Military Police Company charged with abuses at Abu Ghraib, photos of which caused a worldwide uproar.

Two from that unit, including Private First Class Lynndie England, who was pictured holding a leash tethered to a naked prisoner, still face trial.

Several witnesses at another Abu Ghraib trial last month testified about abuses from Sergeant Davis and Specialist Krol at the notorious prison that once served as a torture centre under Saddam Hussein.

Sergeant Davis argued that he and other guards roughed up prisoners at the behest of intelligence officials who wanted to extract information from the prisoners.

“Basically, when the intelligence personnel, when they bring them down there, anyone that comes in there with intelligence value, they want to interrogate them and they would ask you to loosen them up,” Sergeant Davis told America’s ABC News last year.

“Basically, just rough them up a little bit, get them scared. Don’t hurt them or anything like that, which I didn’t do. No one was injured from what I did,” he said.

Under the plea agreement, expected to result in a sentence lower than the original eight and a half years he faced, Sergeant Davis admitted his guilt on three charges: dereliction of duty, making a false official statement and battery.

The court will choose a military jury tomorrow to decide the punishment.