The embassy report cautions that "disclosure of a secret prison in which Sunni Arabs were systematically tortured would not only become an international embarrassment, but would also likely compromise the prime minister's ability to put together a viable government coalition with him at the helm."
Maliki's main political rival, Iyad Allawi, narrowly defeated him in parliamentary elections last month. Allawi, a secular Shiite, drew on dissatisfaction in Sunni regions around central Iraq. In the interview, Maliki invited Allawi to join him in forming a new government. But news of a secret prison that falls under the jurisdiction of the prime minister's military office could make it difficult for him to gain any Sunni partners.
The controversy over the secret prison, located at the Old Muthanna airport in west Baghdad, has also pushed Maliki to begin relinquishing control of two other detention facilities at Camp Honor, a base in Baghdad's Green Zone. The base belongs to the Baghdad Brigade and the Counter-Terrorism Force, elite units that report to the prime minister and are responsible for holding high-level suspects.
Families and lawyers say they find it nearly impossible to visit the Camp Honor facilities. The Justice Ministry is now assuming supervision of the Green Zone jails, although Maliki's offices will continue to command directly the military units.
The 431 detainees brought down from Nineveh were initially held at Camp Honor. Interrogations began after they were transferred to the prison at the Old Muthanna airport.
According to the U.S. Embassy report and interviews with Iraqi officials, two separate investigative committees questioned the detainees and abused them. During the day, there were interrogators from the Iraqi judiciary. In the late afternoon they came from the Baghdad Brigade.
The embassy report says that at least four of the investigators from the Baghdad Brigade are believed to have been indicted for torture in 2006. The charges against them at the time included selling Sunni Arab detainees held at a national police facility to Shiite militias to be killed.
In December, the Human Rights Ministry asked the judiciary to investigate Baghdad Brigade interrogators over allegations of torture at Camp Honor, but hasn't received an answer, Iraqi officials said.
With the secret facility at the old airport being shut down, and both Maliki and Salim, the human rights minister, hailing what they regard as progress, some Iraqis with knowledge of the security apparatus say they are worried that nothing will really change.
One former lawmaker with great knowledge of the prime minister's security offices called for radical change in the next government. "This is the beginning. We have to hold people accountable," the former lawmaker said. "It's a coverup of torture."