The government's system for tracking foreign students is inadequate and planned improvements won't be ready by a January deadline, the Justice Department reported Monday after examining the movements of two terrorists who flew hijacked jetliners into the World Trade Center.

The 188-page report from the department's Office of Inspector General faults "untimely and significantly flawed" procedures at the beleaguered Immigration and Naturalization Service. It indicates that a 10-month paperwork backlog allowed Mohamed Atta and his cousin, Marwan Al-Shehhi, to finish flight-training at a Florida school more than six months before U.S. officials even could decide whether to give them permission.

But the report does not suggest that INS could have identified Atta and Al-Shehhi as potential terrorists before Sept. 11, or that INS acted improperly in allowing each to enter the country three times.

"As we have said many times before, there was not intelligence information available that these men were terrorists or a threat to the United States at the time of their admission," INS spokesman William Strassberger said.

The report describes computer information that is at the heart of the method for tracking foreign students as "riddled with inaccuracies" and relying on information in paperwork from schools that is "incomplete and unreliable."

But a new system, dubbed "Sevis," will not be ready by a January 2003 deadline and so many questions remain unresolved about how INS will operate it that its impact "will be minimal" unless improvements are made, the report said.

Attorney General John Ashcroft asked the inspector general to investigate why the INS sent visa approval notices for Atta and Al-Shehhi to the Florida flight school in March, more than six months after the terror attacks against New York and Washington. The report faulted the INS for not pulling these follow-up notifications out of its system after the attacks.

"No one thought to even inquire" where Atta's and Al-Shehhi's paperwork was after Sept. 11, the report said. "This was a widespread failure on the part of many individuals in the INS."

The report also said the INS should not have formally approved the requests by Atta and Al-Shehhi for flight training because they left the country before the government gave them permission to become students. But it also noted that when INS finally approved their requests in July and August 2001, the two already had completed training at Huffman Aviation in Venice, Fla. They finished in December 2000.

U.S. authorities believe Atta, an Egyptian, flew American Airlines Flight 11 into the north tower of the trade center, and Al-Shehhi, from the United Arab Emirates, flew United Airlines Flight 175 into the trade center's south tower.

The report faults INS for ultimately approving the requests for flight training — however late — because Atta, believed to be the leader of the hijackers, flew to Madrid and Switzerland, and Al-Shehhi flew to Morocco and the Netherlands while immigration officials were considering their applications.

Requests from immigrants who leave the United States before the INS grants approval are deemed "abandonments" and should be rejected, the inspector general found.

"If the (INS) adjudicator had full information, he should have denied their applications," the report said.

Another inspector general, James Huse Jr. of the Social Security Administration, issued a report saying as many as one in 12 foreigners obtaining new Social Security numbers illegally use fake documents to acquire the cards.

Some of the hijackers involved in the terrorist attacks had illegally obtained Social Security numbers and used them to get credit cards and open bank accounts.

Huse said a preliminary investigation found that about 8 percent, or more than 100,000 of the 1.2 million original Social Security numbers assigned to noncitizens in 2000, may have been obtained with invalid immigration documents.

The Justice Department report offers an unprecedented glimpse into the movements of the two hijackers — and their interactions with U.S. immigration authorities — during the months preceding the Sept. 11 attacks.

Atta returned to the United States for the third and last time on July 19, arriving at Hartsfield Atlanta International Airport. Al-Shehhi arrived for the last time on May 2 at Miami International Airport. Each time the men arrived, they were routinely questioned and admitted.

"There is a limited written record and the inspectors recalled little if anything," Inspector General Glenn A. Fine said. "But there is no evidence that anything was brought to their attention to suggest they were here for terrorist purposes."

Atta underwent additional questioning when he arrived Jan. 10 at Miami, and Al-Shehhi underwent additional questioning Jan. 18 at John F. Kennedy Airport in New York. The report said INS officials knew the pair had previously requested permission to become students and should have presented student visas, not tourist visas.

But the oversight report noted that Atta and Al-Shehhi would have been permitted into the United States if they had told inspectors they planned to attend classes part-time, and it said the INS routinely granted waivers to students before Sept. 11 without the proper paperwork.

"The INS' prevailing philosophy in dealing with foreign students ... before Sept. 11 was that students were not a concern or a significant risk worthy of special scrutiny," the report said.