The Interior Department's inspector general is reviewing the contracting procedures that allowed the Army to hire civilian interrogators in Iraq and has blocked the Army from using the contract to place new orders with Arlington-based CACI International Inc., an agency spokesman said yesterday.

It was under this contract that CACI's Steven A. Stefanowicz worked as an interrogator at the Abu Ghraib prison near Baghdad. An Army report on abuses at the prison accused Stefanowicz of encouraging soldiers to set conditions for interrogations and says he "clearly knew his instructions equated to physical abuse." Stefanowicz's lawyer has said his client was wrongly accused.

CACI's work was performed for the Defense Department, but managed by Interior, sparking questions about whether the government properly supervised the order.

In a news conference yesterday, Interior spokesman Frank Quimby defended the agency's performance, saying its role was not to oversee the work but simply to perform administrative tasks like paying billings and recording contracting modifications. He said the Army is responsible for overseeing the work of CACI's employees and it has not reported any problems to Interior.

"The Department of Interior received no indication . . . that anything was amiss with the contractor's performance," Quimby said. An Army representative told Interior last week that he "is satisfied with CACI's personnel and performance."

Although Interior will not allow the Army to place new orders under the contract, work already underway will continue, Quimby said.

The contract was first awarded to Premier Technology Group Inc., a Fairfax defense contractor, in 1998 by the Army acquisition center at Fort Huachuca in Sierra Vista, Ariz. In January 2001, the center was taken over by the Interior Department as part of the Defense Department's effort to reduce and streamline its acquisition operations.

The contract, which is officially called a blanket-purchase agreement and has a $500 million limit, was then reissued by Interior. Blanket-purchase agreements are large, vaguely worded contracts designed to give agencies flexibility and to speed up purchases. Critics say these open-ended contracts allow agencies to skirt public oversight.

A year ago CACI acquired Premier Technology Group. In August, Command Joint Task Force-7, the unit overseeing operations in Iraq, decided it wanted CACI to provide interrogators under the blanket-purchase agreement, and informed Interior of its plan.

Because the blanket-purchase agreement was by that time an Interior contract, an Interior official was required to evaluate the new orders to make sure the work was not "outside the scope" of the contract, said Quimby, and that CACI was charging the government appropriately.

The contract was for technology services, but Interior's contracting officer "was convinced under his own guidelines" that the Army could request CACI's help with interrogations because the order included computer integration and data processing work, Quimby said. Interior thus issued a $19.9 million order for the work.

In December 2003, the contract was used again to hire CACI for counterintelligence support in a deal worth $21.8 million.

Design and oversight of the interrogation project was done by an Army employee in Iraq, who was supposed to bring any problems to the attention of Interior's contracting officer. But Quimby conceded that communication between the two has been "incremental and sporadic."

Charles Tiefer, professor of government contracts at the University of Baltimore School of Law, said: "This is a war situation and I don't know what the Department of Interior is doing out there. "

The purchase of services through an Interior Department contractor "sounds like a formula for having little or no oversight and a real potential for abuse, " Tiefer said.

CACI and Premier Technology performed 81 tasks under the blanket-purchase agreement; 11 of those projects have involved work in Iraq. Twenty-seven of CACI's employees work in Iraq as interrogators.

The Army is not required to issue requests for competitive bids when it wants to hire Premier Technology or CACI under the blanket-purchase agreement, nor is it required to disclose the type of work being done under that contract or the price paid for those services.