The Center for Constitutional Rights yesterday sued CACI International Inc. and Titan Corp. on behalf of several Iraqi prisoners, accusing the government contractors of conspiring with U.S. officials to abuse Iraqi detainees and failing to properly supervise their own employees.

The New York-based nonprofit legal center, which has also filed lawsuits asking that detainees being held at Guantanamo Bay in Cuba be given access to counsel, accused Arlington-based CACI and San Diego-based Titan of failing to properly screen employees and of not supervising them adequately. The lawsuit seeks monetary damages and an injunction preventing the contractors from obtaining new government contracts.

Titan and CACI officials denied the allegations. "We believe this lawsuit to be frivolous and we will vigorously defend against it," said Wil Williams, a spokesman for Titan. "We have never had control over prisoners or how they were handled."

"CACI summarily rejects and denies the ill-informed, slanderous and malicious allegations of the lawsuit that attempts to malign the work that we do on behalf of the U.S. government around the world and in Iraq," the company said in a statement.

The government contractors were named in an Army report about the physical abuse and sexual humiliation of prisoners at the Abu Ghraib prison outside of Baghdad, where CACI provided interrogators and Titan supplied linguists.

The lawsuit will face several hurdles, including proving that CACI and Titan knew or should have know that the alleged abuses would occur and that they didn't properly supervise their employees, legal experts said.

The suit relies on the Alien Tort Claims Act, which has been increasingly used by groups or individuals seeking to hold U.S. corporations responsible for conduct in foreign countries that lack adequate court systems, said Dan Guttman, a fellow at the Center for Study of the American Government at John Hopkins University. For example, the law has been central to suits filed against oil companies working in Myanmar, formerly Burma, where plaintiffs accuse the companies of aiding in government human rights abuses of villagers, he said.

"Right now it's the subject of tremendous interest, and cases that will decide its potential judicial reach are winding their way through the judicial system," Guttman said.

One plaintiff in the latest lawsuit, Sami Abbas Al Rawi, claims he was kicked, beaten, hooded for long periods, deprived of food and subjected to loud rock music, according to the lawsuit. Another plaintiff identified only as Rasheed said he was beaten on his feet with iron skewers and electrocuted on his tongue and anus. Another plaintiff called Neisef alleges he was sexually abused by a female conspirator for 30 minutes, forced to touch other detainees' body parts and threatened with attack dogs, the suit says. The plaintiffs in the lawsuits are not portrayed in any of the photos that have become emblematic of abuses at the prison, their attorneys said.

None of the plaintiffs could name the individual contractors who committed the alleged abuses. Their legal representation, which also includes the Philadelphia law firm Montgomery, McCracken, Walker and Rhoads, said the plaintiffs knew the individuals were civilians by what they were wearing and are able to describe physical characteristics of the people they are accusing. Those specific contractors will be identified later, the attorneys said.

The lawsuit names CACI interrogator Stephen A. Stefanowicz as a defendant, based on an Army investigation, according to attorneys. The Army's report accused Stefanowicz of encouraging soldiers to set conditions for interrogations and that he "clearly knew his instructions equated to physical abuse."

Stefanowicz's lawyer yesterday reiterated previous statements that his client did nothing wrong. "I would say that these allegations against Mr. Stefanowicz are outrageous and baseless and made without any regard to any apparent factual investigation whatsoever," said Henry E. Hockeimer Jr., an attorney with Hangley Aronchick Segal & Pudlin in Philadelphia.

Also named in the lawsuit is Adel Nakhla, a Titan translator, who was listed both as a suspect and witness in the Army report, although there are no allegations spelled out. Titan terminated Nakhla last month but has not explained why. Calls to his attorney were not returned yesterday.

The third employee named in the lawsuit, John B. Israel, is accused in the Army report of lying to investigators about seeing interrogations that violated the rules. Israel could not be reached for comment. He worked for a Titan subcontractor, SOS Interpreting Ltd.

CACI is already under investigation by the General Services Administration, which is exploring whether the company violated contracting rules in obtaining the interrogation work and should be banned from future government contracts.

Allegations of abuse at the prison are the subject of several investigations. On Tuesday, Attorney General John D. Ashcroft told Congress that a special team of prosecutors had been assembled in the U.S. attorney's office in Alexandria to investigate violations of the Torture Act.

Staff writer Ellen McCarthy contributed to this report.