Authorities violated the civil rights of hundreds of immigrants detained after the Sept. 11, 2001, attacks and demonstrated "a pattern of physical and verbal abuse" at a federal prison where 84 of them were held, according to a long-awaited Justice Department report released yesterday.

According to a review by its Office of the Inspector General, the Justice Department instituted a "no bond" policy for all detainees connected to the terrorism probe after the attacks -- even though immigration officials quickly questioned the policy's legality.

Without bail, terrorism suspects remained in jail for an average of nearly three months, much longer than the FBI projected before it cleared most of them for release, the report said. In addition, detainees faced monumental difficulties and weeks of delay before they were allowed to make phone calls and find lawyers. Some were kept for months in cells illuminated 24 hours a day and were escorted in handcuffs, leg irons and waist chains.

In one Brooklyn detention facility, some detainees complained of being slammed against walls and taunted by guards, claims that inspectors found credible.

The 198-page report by Inspector General Glenn A. Fine is the most thorough account to date of the government's handling of 762 immigrants -- most of Arab and South Asian descent -- taken into custody during the nationwide terrorism probe. All had violated immigration laws in some way. The inquiry focused on two detention facilities that housed the majority of the detainees, the federal Metropolitan Detention Center in Brooklyn and the Passaic County jail in Paterson, N.J.

In the chaotic aftermath of the attacks on the World Trade Center and the Pentagon, senior Justice Department officials devised a far-reaching strategy to give investigators as much time as possible to determine whether detainees were connected to terrorism, according to the report.

The report, which emerged from internal government documents and more than 100 interviews with U.S. officials and detainees, "recognized the enormous challenges and difficult circumstances confronting the [Justice] Department in responding to the terrorist attacks." But the inspector general "found significant problems in the way the September 11 detainees were treated."

Only one detainee, Zacarias Moussaoui, who was in custody before the attacks, has been charged with a terrorism-related crime.

Justice Department spokeswoman Barbara Comstock said the report is "fully consistent with what courts have ruled over and over -- that our actions are fully within the law and necessary to protect the American people. We make no apologies for finding every legal way possible to protect the American public from further terrorist attacks."

In a letter attached to the report, Deputy Attorney General Larry Thompson wrote: "The detention of those illegal aliens suspected of involvement with terrorism was paramount. . . . My staff understood that the immigration authorities of the Department should be used to keep such people in custody until we could satisfy ourselves -- by the FBI clearance process -- that they did not mean to do us harm. Given those circumstances, I respectfully submit that it is unfair to criticize the conduct of members of my staff during this period."

However, Anthony D. Romero, executive director of the American Civil Liberties Union, called for congressional hearings into the treatment of detainees following the Sept. 11 attacks. The inspector general's report, he said, may form the basis for a lawsuit against Justice Department employees involved in formulating and executing the policy.

"I think overall the report clearly talks to the wholesale abuse of immigrants' rights in the aftermath of 9/11," Romero said. "Immigrants weren't the enemy, but the war on terrorism quickly turned into a war on immigrants."

Elisa C. Massimino, Washington director for the Lawyers Committee for Human Rights, said that "it's quite clear, more clear than even I expected it to be, that the Justice Department and chiefly the attorney general, was playing this shell game with these detainees, exploiting the immigration rules in order to keep people in custody longer."

Among the findings by the Justice Department's independent, internal investigator:

* Detainees at the Metropolitan Detention Center, a federal prison in Brooklyn, were subjected to "unduly harsh" conditions. Of 19 MDC detainees interviewed by the inspector general's office, 12 reported physical abuse that included guards slamming detainees into walls while they were being transferred. Ten said they were verbally abused. The inspector general's office interviewed 12 correctional officers; each denied witnessing or participating in any active abuse.

Prosecutors, citing lack of evidence, declined to prosecute any of the guards, the report said. However, it revealed that Fine's office is continuing to investigate.

The report said the investigation into alleged abuses was hampered by the destruction of hundreds of hours of videotape from MDC's Special Housing Unit, where the detainees were held. Fine, in an interview, said destruction of the videotapes appeared to be the result of a "general policy" to clear up space after hundreds of hours of filming. "There's no indication they were trying to cover anything up," he said.

* For several weeks after the attacks, Bureau of Prisons officials imposed a "communications blackout" that severely limited detainees' efforts to contact family and attorneys. Even after the blackout was lifted, the designation of the detainees as "Witness Security" inmates frustrated efforts by attorneys, families "and even law enforcement officials" to determine where a detainee was being held, the report said.

* In some cases, the Immigration and Naturalization Service waited more than a month before presenting detainees with charging documents, instead of the agency's stated goal of 72 hours. The delays made it difficult for the detainees to "understand why they were being held, obtain legal counsel, and request a bond hearing," the report concluded.

In a Sept. 17, 2001, memorandum, Attorney General John D. Ashcroft declared that the Justice Department sought to prevent future acts of terrorism by arresting and detaining violators who "have been identified as persons who participate in, or lend support to, terrorist activities. Federal law enforcement agencies and the United States Attorneys' Offices will use every available law enforcement tool to incapacitate these individuals and their organizations."

A senior federal law enforcement official, who spoke on condition of anonymity, said that among the 762 detainees were some who are "very dangerous and known to be associated with terrorists." One was a roommate of one of the Sept. 11 hijackers, the official said, and another acknowledged attending terrorist training camps in Afghanistan.

Citizens of more than 20 countries were among the detainees, according to the report. The largest number, 254, or 33 percent, came from Pakistan, more than twice as many as from any other country.

Authorities held suspects on immigration violations such as overstaying their visas or working without proper permits while investigators sought to determine whether they were connected to terrorism. According to the report, the Justice Department issued a "hold until cleared" policy. The policy was "not memorialized in writing," according to the report, but was clearly understood by INS and FBI officials in the field.

The inspector general found that Stuart Levey, the associate deputy attorney general responsible for oversight of immigration issues, communicated the directive to the INS and the FBI. The policy was based on the mistaken conclusion that suspects would be cleared within days. Instead, the report concluded, the clearance process took an average of 80 days "because it was understaffed and not given sufficient priority by the FBI."

As the process lagged, INS officials became concerned about holding detainees indefinitely under the "no bond" policy, and after immigration judges had ordered them removed from the United States, according to the report.

The report concluded that the FBI did not adequately separate immigration violators with apparent links to terrorism from those they simply discovered during their manhunt.

A detainee's treatment depended largely on the institution to which he was sent after investigators determined whether he was designated as "high interest," "of interest" or "of undetermined interest to the investigation."

"High interest" detainees were usually sent to Bureau of Prisons facilities around the country, including the Metropolitan Detention Center. Shortly after the attacks, according to the report, BOP officials ordered the construction of an "Administrative Maximum" Special Housing Unit there to house terrorism suspects.

The detainees were kept in their cells at least 23 hours a day. Escort procedures included a "four-man hold" with handcuffs, leg irons and heavy chains anytime the detainees were moved out of their cells.

Detainees who were designated as "of interest" or "of undetermined interest" were jailed in "significantly less harsh" conditions, according to the report. At Passaic County jail, the 400 such detainees were generally held in much less restrictive conditions and there was little physical abuse, the report concluded.

Staff writer Susan Schmidt and research editor Margot Williams contributed to this report.