BY ALFONSO CHARDY

 In the clearest indication yet of how much the Sept. 11 terrorist attacks have altered the national immigration climate, the United States and Mexico agreed this week to delay an agreement that might have given millions of undocumented Mexicans work and residence papers, U.S. and Mexican officials said Wednesday.

 The decision to continue working on such an agreement into next year came at the end of bilateral Mexican-American talks on the issue Tuesday in Washington at which senior U.S. and Mexican government officials acknowledged their inability to conclude an accord in the aftermath of the terrorist attacks.

 The new stance departs sharply from an original deadline to frame an agreement before year's end set by Mexican President Vicente Fox when he traveled to Washington for a state visit Sept. 5.

 The delay also underscores the broader efforts by the Bush administration to tighten -- not loosen -- immigration laws and regulations with a view to improving national security.

 Since Sept. 11, more than 1,000 foreign nationals -- mostly Arabs -- have been detained indefinitely on either suspicion of a connection to the terrorist plot or as witnesses or potential witnesses in the case.

 In addition, the State Department has slowed down the processing of visa applications for young men from Arab and Muslim nations and the arrival of already approved foreign refugees.

 Domestically, the Immigration and Naturalization Service has delayed the release of some detained asylum applicants, has tightened regulations to release foreign
 nationals in long-term detention and made it more difficult to enter the country with more thorough scrutiny at border crossings.

 ``Reaching a migration agreement before year's end is no longer possible and we understand that,'' said a senior Mexican official familiar with the bilateral negotiations. ``Mexico is sensitive to the issues of national security raised by Sept. 11.''

 In a statement Wednesday night, the State Department said that while the Mexican talks had not been ``deferred,'' the next meeting between Mexican and U.S.
 negotiators will not take place until January.

 When Bush received Fox at the start of the Mexican state visit Sept. 5, Fox pressed for a quick agreement during a speech at the White House welcoming ceremony.

 ``We must, and we can, reach an agreement on migration before the end of this very year,'' Fox said at the time.

 American officials echoed the view that delay is inevitable, but noted that the talks will continue over the next weeks and months.

 ``President Bush has made it clear that immigration is on the agenda and we will continue to discuss the immigration process with Mexico,'' said acting U.S. Assistant
 Secretary of State for Latin American and Caribbean Affairs Lino Gutierrez.

 Nevertheless, the failure to strike an agreement this year unsettled U.S. immigration advocates who had hoped to use a Mexican agreement as a model for similar
 accords covering millions of other undocumented foreign nationals.

 ``It's unfortunate,'' said Cheryl Little, executive director of the Miami-based Florida Immigrant Advocacy Center. ``What's so sad about this is that it wasn't just Mexicans who were holding out hope that they would finally have an opportunity to regularize their status. There were many different groups who held out hope as well.''

 Mexican accord supporters urged patience.

 ``We will continue to advocate for a policy that treats people in similar situations similarly,'' said Lisa Navarrete, spokeswoman in Washington for the National Council of La Raza, a group involved in seeking a Mexico migration accord.

 Navarrete said she was not surprised by the delay, but noted that the talks have not collapsed.

 ``Sept. 11 changed everything and rightfully so,'' Navarrete said. ``We are now a country at war and we have to deal with our first priority which needs to be this threat to our nation.

 ``But it was very clear when President Fox, one of the first world leaders to call President Bush to extend condolences to the American people, in the conversation with President Bush made it clear that he wanted to keep going forward.''

 Herald staff writer Andres Oppenheimer contributed to this report.

                                   © 2001