WASHINGTON - Under pressure from Congress and the public, the Homeland Security Department extended the time for people to comment on its computerized risk assessment system for international travelers.

The deadline was pushed back from Dec. 4 to Dec. 29, department spokesman Jarrod Agen said Tuesday.

By Tuesday, the department had received 59 public comments. All but one either opposed the system outright as a violation of privacy and other laws or called for better means for people to correct any errors in the data. One law firm representing ship owners and importers sought more time for comment.

Rep. Bennie Thompson, D-Miss., who will become chairman of the House Homeland Security Committee when Democrats take control of Congress in January, wrote Homeland Security Secretary Michael Chertoff seeking extension of the comment period.

Based on a briefing that committee staff received about the system last Friday, Thompson wrote "serious concerns have arisen that, with respect to U.S. citizens and possibly lawful permanent aliens, some elements of ATS as practiced may constitute violations of privacy or civil rights."

The Associated Press reported last Thursday that for four years Customs and Border Protection agents have been using the Automatic Targeting System, or ATS, to produce assessments of the risk that any of the millions of people crossing U.S. borders, including Americans, are terrorists or criminals.

Almost every traveler entering or leaving the country is evaluated by the ATS computers, but they are not allowed to see the assessment of them or directly challenge its accuracy. The government intends to keep the assessments 40 years and the data on which they are based for up to 40 years.

Sen. Patrick Leahy, D-Vt., incoming chair of the Senate Judiciary Committee, promised more congressional scrutiny next year of the government's anti-terrorist databases and called the ATS scheme "simply incredible."

The assessments are based on applying so-called rules, which are actually assumptions based on the past behavior of terrorists and criminals, to the person's travel records, including where they are from, how they paid for tickets, their motor vehicle records, past one-way travel, seating preference and what kind of meals they ordered.

The government's first acknowledgment that ATS was producing risk assessments of travelers came in a Nov. 2 notice in the Federal Register, a dry daily compendium of rules and regulations.

Although that notice said ATS would be implemented Dec. 4 unless negative comments dissuaded officials, ATS has been operational for some time and no changes were planned for Dec. 4, Toby Levin, senior adviser in Homeland Security's privacy office told the AP.

The notice was only designed "to give greater transparency" to what Homeland Security was already doing, she said.

In fact, Jayson Ahern, assistant commissioner of Customs and Border Protection, said federal agents had used ATS to develop risk assessments of travelers since the late 1990s, but the program had mushroomed in 2002 when legislation spawned by the Sept. 11, 2001, terrorist attacks took effect. That legislation required all air and cruise lines to electronically give Homeland Security advance lists of all their incoming and outgoing passengers and crew members.

In addition, Ahern said Amtrak voluntarily provides passenger data on rail travelers between the U.S. and Canada and border agents keep track of many of the people and drivers who enter or leave land border crossings. Ahern said ATS is designed to pick out people who are not already on watch lists or wanted by law enforcement.

Homeland Security's Agen said a new notice announcing the extension was sent Tuesday to the Federal Register and would be published in a few days.