Staff Sgt. Ivan "Chip" Frederick (search), who last week agreed to plead guilty to some charges in the Abu Ghraib abuse scandal, said in an interview published Sunday that "secret services" operating in the jail encouraged the humilation of prisoners.

But Frederick said he was taking responsiblity for what he had done and urged other defendants to do the same.

"I will answer for my acts in court, but I hope that others will take my example and take responsibility for their guilt — there are certainly more people responsible for what happened in Abu Ghraib (search) and many of them are not yet charged," Frederick said in the interview with Der Spiegel magazine.

The interview was conducted last week in Mannheim, where Frederick told a military court he would plead guilty at a hearing in Baghdad in October.

Frederick told Der Spiegel that the abuse was already going on at Abu Ghraib when his unit arrived there, and that they were told that was the way military intelligence wanted it done.

"The people from the secret services were always praising us — they said 'do more like that, you're doing good work,"' Frederick said in the interview, published in German. "The secret services had simply set no boundaries. They were looking for concrete results and were not interested in how they were achieved."

"They said 'put the dogs on these prisoners, try to get more information from them, take their food away, their clothes — humiliate them,"' he told the magazine.

An Army investigation released last week said an unidentified civilian contractor worked with and encouraged abuse by Frederick.

Frederick and five other military police currently face charges in the Abu Ghraib case, while a seventh has pleaded guilty and is serving one year in prison. Their defense attorneys have maintained that they were following the direction of civilian contractors and military intelligence in carrying out the abuse.

Frederick is charged with maltreating detainees, conspiracy to maltreat detainees, dereliction of duty and wrongfully committing an indecent act and has not said specifically which counts he will plead guilty to.

During the three days of hearings in Mannheim, prosecutors said at least two military intelligence soldiers would soon be charged and the judge suggested he may force key military intelligence officers to testify, broadening the scope of the prison scandal beyond the 372nd Military Police Company (search), an Army reserve unit from Maryland to which all soldiers facing charges so far were assigned.