Salo Eduardo Levy, Western Union's Mexico director, echoed that theme at a September meeting of industry executives. "We have customers calling agents before they go: 'Is it safe? Is La Migra around?' "

A 2006 survey by the Inter-American Development Bank found that illegal immigrants made up about 40 percent of the Latin Americans in the United States who used money transfer companies.

Western Union says it does not know what share of its customers are illegal immigrants, but at times it has made pitches directly to them. As Central Americans surged across the Texas border in 1999, an overflowing federal detention center bused them to a homeless shelter in Brownsville. Western Union sponsored a lunch there, dispensing T-shirts, bandannas and fliers in Spanish with the company's toll-free telephone number.

Western Union also held marketing events around the same time for people deported from the United States to Honduras and El Salvador.

"They would arrive in a special holding area, and we would have an agent in there — a young lady in tight jeans, tight T-shirt" to promote Western Union products, said a former company official who spoke only on the condition of anonymity. "We knew that within a week they would be back on their way to the U.S."

Fred Niehaus, a Western Union vice president, said, "I can tell you that's something the company would not do now."

Immigration and politics

Western Union's views on immigration have brought conflicts with Tancredo, the Republican congressman who represents the Denver suburb where the company has its headquarters. Three years ago, when Tancredo, a fierce critic of illegal immigration, proposed taxing the money that migrants send, First Data formed a political action committee to drive him from office.

"We're tired of his antics," Niehaus told The Rocky Mountain News. "We're opting for change."

After winning re-election, Tancredo attacked Western Union for co-sponsoring a Spanish guide that he said promoted illegal immigration. The guide said that schools and clinics would not check migrants' papers and advised them to "always carry the name and number of an attorney."

In a recent interview, Tancredo, who is running for president, said the company's activities occupied "a gray area" between aggressive marketing and "aiding and abetting illegal immigration."

"Western Union wants to encourage illegal immigration in order to expand the number of people in their market," he said. "Believe me, if I were president, I would ask the Justice Department to look into it."

In 2004, Charles T. Fote, then First Data's chairman, gave a speech calling for "comprehensive" reform, a term used by supporters of legalization plans for illegal immigrants.